SECOND TERM E-LEARNING NOTESUBJECT: PHYSICS CLASS: SS 1SCHEME OF WORK WEEK TOPICHeat Energy, Concept of Heat and Temperature, Effects of Heat and UsesThermometer and Its Type, Evaporation and BoilingExpansion of Solid, Effect and Applications of ExpansionExpansivity and Its Application – Linear, Area and Volume. Anomalous Expansion of Water. Real and Apparent ExpansivityHeat Transfer – Conduction, Convection, Radiation and Their ApplicationsElectric Charges – Production, Types, Distribution and StorageGold Leaf Electroscope and its Uses. Lighting and Lighting ConductorFields – Concept and Types of Field. Gravitational and Magnetic Field, Force of GravityElectric Field – Line of Forces, Properties of Line of Force, Description and Properties of Force FieldProduction of Continuous Electric CurrentREFERENCE BOOKNew School Physics By M.W AnyakohaSenior Secondary School Physics By P.N OkekeWEEK ONETOPIC: Heat Energy, Concept of Heat and Temperature and Effects of HeatCONTENTConcept of HeatTemperatureEffect of Heat on bodies.Concept of HeatHeat is a concept of physics that deals with the study of relative motion of fluid (liquid and gas) from one body to another. It is a form of energy that can be transferred from one body due to temperature differences.TemperatureTemperature is the degree of hotness and coldness of a body or an object. It is a scalar quantity, measured in Kelvin. Heat and Temperature are similar but not the sameDifferences between Heat and Temperature Heat is a measure of the total internal energy of a body while temperature is the degree of hotness or coldness of the body.Heat takes place due to temperature difference while temperature occurs due to slight change of substance.Heat is measured in joules while temperature is measured in Kelvin / Celsius.Effect of Heat When heat is applied to a body the following effect may occurExpansion: when heat is applied, volumes increases while density decreases.Change in temperature: When heat is added on a body, the temperature increasesChange of state: melting, freezing, condensation, evaporation etc.Thermion emission: Addition of heat on metal may result in the emission of electron from the surface of the metalPhoto electric emission: The emission of electron when sufficient light of high frequency is illuminated on a metal surface e.g. zinc plate.EVALUATION Differentiate between heat and temperature.Mention five effect of heat.Reading Assignmentwww.google.com (click on google search, type “concept of heat”, click on search) and New School Physics pg36. WEEKEND ASSIGNMENT Which of the following is not an effect of heat? A. expansion B. contraction C. change of state. D. increase in weightTemperature can be measured in the following units except A. degree celsius B. kelvin C. degree Fahrenheit D. centigrade-meterWhen heat is extracted from water it changes from liquid to gas. What is this process called....................The process of by which a gas is converted to a solid is called .................Fahrenheit is a unit of ............................... THEORYDifferentiate between heat and temperature. Mention five effect of heat.WEEK TWOTOPIC: Thermometer and Its Type. Evaporation and BoilingCONTENTThermometer and Their Thermometric SubstanceFixed Point of Thermometer Evaporation and BoilingThermometer and Their Thermometric SubstanceThermometric substances are substances which changes in proportion to temperature. ADVANTAGES OF MERCURY AS A THERMOMETRIC SUBSTANCEMercury does not wet glassMercury response quickly to slight change in temperatureThe liquid does not vaporize easilyMercury is opaque Hence, it can be seen easilyIt has a regular or uniform expansion.DISADVANTAGESMercury is expensiveMercury can not be used to measure very low temperature because it’s freezing point - 39˚CADVANTAGES OF ALCOHOL AS A THERMOMETRIC SUBSTANCEAlcohol is less expensive than mercury It has larger expansion on heating than mercury (it expands 6 times more than mercury).It can be used to measure very low temperature.DISADVANTAGESIt is not opaque and so most be coloredIt vaporizes easilyIt wet glassIt has an irregular expansionIt has low boiling point of 78˚CCONSTANT VOLUME GAS THERMOMETERIt gives more accurate measurement of temperature than any other thermometerIt is very sensitive and can measure wider range of temperatureDISADVANTAGESIt is very expensive and so require handling with special careIt is very cumbersomeEVALUATIONWhat advantage does a constant volume gas thermometer has over other thermometers?Mention five types of thermometer, their thermometric substance and physical property.FIXED POINT OF THERMOMETERFixed temperature point are two reference temperature (usually upper and lower fix point) chosen, when preparing a scale for reading temperatures.Upper Fixed Point: is the temperature of steam from pure water at the normal atmospheric pressure.Lower Fixed Point: is the temperature of mixture of pure ice and water at normal pressure.Fundamental Intervals: is the interval between the upper and lower fixed point. 1000C 373K 2120F 00C 273K 320FCelsius Scale Kelvin Scale Farenheit ScaleREASON WHY WATER IS NOT USED AS A THERMOMETRICWater wet glassThey are colour lessIt does not expand uniformlyIt has small range of expansion (0˚C to 100˚C)CLINICAL THERMOMETERIt is used for measuring the temperature of human body. The body temperature ranges from (35˚C to 45˚C). It is not advisable to sterilize a clinical thermometer in boiling water because a short range of 35˚C to 43˚C which shall result to Cracking or breaking of thermometer due to excessive expansion of the mercury.Malfunction of the thermometer due to over expansion of the capillary tube and the mercury inside the bulb.Evaporation and BoilingEvaporation is the process where a liquid turns into vapor below its boiling point. Evaporation takes place at all temperature. Wind assist evaporation.Boling is the change from liquid to vapor at the boiling point. It occurs throughout the entire volume of the liquid. Wind has no effect on boiling.EVALUATIONWhy is water not used as a thermometric substance?Differentiate between evaporation and boiling.Reading Assignmentwww.google.com (click on google search, type “temperature & its measurement”, click on search) and New School Physics pg 202 - 209 WEEKEND ASSIGNMENTThe clinical thermometer is characterized by having a A.wide range of temperature B. wide bore C. long stem D. constrictionA short response time is obtained in a liquid - in-glass thermometer when the A. bulb is large and thick walled B. bulb is small and thin walled C. stem is long and thin D.bulb is thin walled and the liquid is a good conductor of heat.Change in volume with temperature is the physical propety of ………. thermometer A. constant volume gas B. liquid-in-glass C. resistant D. thermoelectricConvert 270C to kelvin A. 290K B. 300K C. 3000C D. 310KThe following are units of temperature except A. kelvin B. degree Celsius C. ampere D. Fahrenheit THEORYMention five types of thermometer, their thermometric substance and physical property.Why is it not advisable to sterilize a clinical thermometer in boiling water?WEEK THREETOPIC: Expansion of Solid, Effect and Applications of ExpansionCONTENTEffect and Application of Thermal Expansion of SolidAdvantages and Disadvantages of Thermal Expansion of SolidEffect and Application of Thermal Expansion of SolidWhen hot water is poured in a glass tumbler, it might crack due to the uneven expansion of the inner wall of the tumbler.The cracking noise of zinc roof during the day and night.Thermal expansion of solid is used in the construction of bridges in which one side is fixed and the other is placed on rollers to allow for expansion.The stopper of a bottle can be removed due to the expansion of the glass.In the construction of concrete pavement, little spaces are left within the concrete to allow for expansion.Gaps are left in the construction of railway tracks to give room for expansion.Bimetallic stripes are use in thermostat for controlling or regulating the flow of electric current.Advantages and Disadvantages of Thermal Expansion of SolidAdvantagesFire alarm e.g. electric bellThe fittings of wheels in rimsBimetallic thermometerRed hot rivet in ship buildingBimetallic stripes used in thermometer e.g. electric cooker etcDisadvantagesCracking of drinking glass when hot liquid poured insideIf the balance wheel of a watch expands the time will be fast and if the balance wheel of a watch contrasts the time will be slowExpansion of metal of concrete bridges which can lead to eventual after a long periodSagging of overhead wire due to contraction in winter seasonExpansion of railway tracks thereby forming distant railway tracks.Bursting of water metal pipes.EVALUATIONMention four effect of thermal expansion of solid.Mention four the advantages and disadvantages of thermal expansion of solid.Reading Assignmentwww.google.com (click on google search, type “expansion of solid”, click on search) and New School Physics pg 37 – 42.WEEKEND ASSIGNMENTGaps are left in the construction of railway tracks to give room for …………. A. contraction B. evaporation C. expansion D. vaporizationWhen hot water is poured in a glass tumbler, it might crack due to the ………… of the inner walls of the tumbler A. even expansion B. uneven expansion C. uneven contraction D. even contractionThe stopper of a bottle can be removed due to the ………… of the glass A. contraction B. expansion C. evaporation D. none of the aboveThe following are advantages of thermal expansion of solids except A. bimetallic thermometer B. fire alarm C. sagging of overhead wire D. fitting of wheels in rimsIf heat is removed from solids they A. contract B. evaporate C. expand D. none of the aboveTHEORYMention four effects of thermal expansion of solid.Mention four the advantages and disadvantages of thermal expansion of solid. WEEK FOURTOPIC: Expansivity and Its Application – Linear, Area and Volume. AnomalousExpansion of Water. Real and Apparent ExpansivityCONTENTLinear Expansivity of SolidArea Expansivity of SolidCubic Expansivity of solid and LiquidAnomalous Behavior of WaterLinear ExpansivityLinear expansivity of a solid can be defined as increase in length per unit length, per unit degree rise in temperature. It is denoted by (α) and measure in per Kelvin or per degree Celsius. Mathematical representation α= L2 – L1 L1 (Ө2 - Ө1) ______________ (i)Linear expansivity (α)= increase in length Unit length x temp changeL1 is the original length Ө1 is the initial temperatureL2 is the final length Ө2 is the final temperature▲L = L2 – L1▲Ө = Ө2 - Ө1 α = ▲L L1 ▲Ө ________ (ii)α = L2 – L1 L1 X ▲ӨL2 – L1 = α L1 ▲ӨL2 = L1 + X L1 ▲Ө L2 = L1 (1 + X ▲Ө)N.B. ▲L = L2 – L1 ▲Ө = Ө2 - Ө1A brass rod is 2m long at a certain temperature. What will be the length for a temperature rise of 100K , if the linear expansivity of brass 18 x 10-6K-1SOLUTIONL1 = 2m, L2 =?, ▲Ө = 100K, α = 18x1o-6k-1 L2 = L1 (1 + α▲Ө)L2 = 2 (1 + (18 X 10-6 X 100)= 2(1 + 0.00018= 2 (1.OOO18)= 2.0036mArea ExpansivityThe area/superficial expansivity is the increase in area of per unit area per degree rise in temperature. It is donated by (β) and measured in per Kelvin and per 8Cβ = A2 – A1 A1 (Ө2 - Ө1)Recall; L2 = L1 (1 + α ▲ Ө)Similarly b2 = b1 (1 + α ▲ Ө)A2 = L1 (1 + α ▲ Ө) X b1 (1 + α ▲ Ө) = L1b1 (1 + α ▲ Ө) (1 + α ▲ Ө)A2 = A1 (1 + 2 α ▲ Ө + (α ▲Ө) ²A2 = A1 (1 + 2 α ▲ Ө)A2 = A1 (1 + β ▲ Ө)EVALUATIONA brass rod is 2m long at a certain temperature. What will be its length for a temperature rise of 90K, if the linear expansivity of brass is 1.8 x 10-6K-1Prove that A2 = A1(1 + β▲ Ө).Volume/Cubic ExpansivityIt is denoted by (Y). It is the increase in volume per unit volume per degree rise in temperatureY = V2 – V1 V1 (Ө2 - Ө1) ___________ (i)Y = 3α _________ (ii)Relationship between α: β: Y: = 1: 2Real and Apparent Cubic Expansivity of WaterReal or absolute cubic expansivity (Yr) .The real / absolute of the liquid is the increase in volume by unit volume per degree rise in temperature.Apparent Cubic Expansivity (Ya)The apparent cubic expansivity is the increase in volume per unit rise when heated in an expansible vessel.Yr = Ya + YAnomalous Behaviour of Water Most liquid except water expand when heated. This abnormal behavior of water is what is refer to as anomalous expansion of water. When water is heated from 00C, it contracts until it reaches 40C and beyond this point, water expands normally. The anomalous expansion of water takes place between 00C and 40C.EVALUATIONWith the aid of a diagram, explain the anomalous behavior of water.Describe an experiment to determine the apparent cubic expansivity of a liquidReading AssignmentNew School Physics pg 38 – 40,43 – 46WEEKEND ASSIGNMENTThe anomalous expansion of water takes place between/at ………………..A. 10C and 40C B. 00C and 40C C. 40C and 250C D. all temperatureThe SI unit of linear expansivity is ……… A. per Celsius B. per Fahrenheit C. per Kelvin D. per JoulesIf the linear expansivity of a solid is 1.8 X 10 -6 k-1, the area expansivity will beA.0.9 X 10 -6 B. 3.6 X 10 -6 C. 1.8 X 10 -6 D. 5.4 X 10-6A metal of length 15.01m is heated until its temperature rises by 600C. If its new length is 15.05, calculate its linear expansivityA. 0.0004/K B. 0.00004/K C. 0.004/K D. 0.04/KThe increase in volume of 10cm3 of mercury when the temperature rises by 1000C is 0.182cm3. What is the cubic expansivity of mercury A. 0.000182/K B. 0.0000182/K C. 0.000187/K D. 0.000178/KTHEORYExplain the anomalous behavior of waterIf a cube metal box made of iron of side 2cm is to be used for construction, and the expected temperature difference is 900C. What will be the expected change in volume of the cube box if the linear expansivity of iron is 1.25 X 10-5. WEEK FIVETOPIC: Heat Transfer – Conduction, Convection, Radiation and Their ApplicationsCONTENTConductionConvectionRadiationThermo FlaskHeat can be transferred by conduction, convection or radiation.CONDUCTIONThis is the process of transfer of heat through a material by vibration of the molecules fixed in position. N.B. Metals that allow heat to pass through them are said to be good conductors of heat. Though all metals are classified as good conductors, they differ in an ability to conduct heat. Non metal (wood / plastic) are bad conductors that does not allow heat to pass through it. Thermal conductivity is simply the ability of a metal to conduct heat.PRACTICAL APPLICATION OF CONDUCTION OF HEATKettle, pans and other utensils made of metals are provided with wooden or ebonite utensils so that heat from to utensils is not conducted.House old source pans are made of metals because metals are good conductors of heat and electricity.Thick brick walls are used in the construction of storage rooms. Bricks are bad conductors of heat, so it will not allow heat to enter the storage room.A stone floor feels cold to the feet than a rug or a carpet on the same floor feels warm.CONVECTIONConvection is the process by which heat energy is transferred in a fluid (liquid or gas) by actual movement of the heated fluid. The direction of the motion of a filter paper indicates the circulation of heated water. Circulation of a liquid is called CONVECTION CURRENT.APPLICATION OF CONVECTIONConvection in liquidDomestic water-boilers.Cooling process of a motorcar vehicle.Land and sea breezes.Land and sea breezesConvectional current set up in land and sea breezes. They occur mainly in coastal regions.Sea breezeDuring the hot season, heat from the sun passes straight from the air with little effect. The land is heated by the sun more quickly than the sea becase:It is a good absorber of heat.It is a good radiator.It has low specific heat capacity.The air near the land thus warms up and rises while air from the sae moves into the land to replace the risen air. Air from the higher atmosphere moves from the sea and then a circulation current is set up. The breeze from the sea is known as the sea breeze.Land breezeDuring the night, land is not heated by the sun, so it cools very quickly. Temperature of the sea drops only slightly and since it has been heated to a very high temperature, it retains more heat as a form of energy. As a result of this, the sea is warmer than the land at night. Convectional current is therefore set in the opposite direction in the day as a result of breeze blowing from land to the sea. This breeze from the land is called land breeze.Convection in gasesChimneys in KitchensVentilation of industrial buildings (up-cast and downcast)BonfiresRoom radiators- when in use, the hot air rising from it can produce a shadow in the room by the sun due to convection.Glider lift- lift for aircraft used in flying sport. It is done by positioning the aircraft towards the roofs of factories where air above is warmer than any other place. The rising convection current is called thermalWind- convection currents in air when hot air rises from the equator and replaced by a colder or denser air from the polar region. Wind depends on earth’s rotation, large masses of land and sea over which it passes and temperature.Air conditional are placed at the top of wall in the room and not on the floor so that the hot air which are less dense rises and are cooled while the colder air which are denser sink down hence. This continuous process of rising and cooling of warm and cold air set up convectional currents which cools the room.RADIATIONRadiation is the process by which heat is transferred or conveyed from one place / point to another without heating the interview medium. In radiation molecules are not involved, it differs from another method because it does not require a medium for heat to be transferred. Heat from the sun reaches us by this method. The energy given out as radiant heat is known as RADIANT ENERGY. This energy displace electrical and magnetic properties and it said to be electromagnetic radiation and the name is INFARED.RADIATION CAN BE DETECTED BYRadiometerThermo-pileLeslie cubeDark surface is good absorber of heat and poor emitter of radiation. Highly polished surface are good emitter of radiation and poor emitter of heat.APPLICATION OF RADIATIONIt is not advisable to wear a dark shirt in the tropical sun.Roofs of factories are coated with aluminum paint.Shinning roofs and outside walls are painted with light colour in hot climate to keep the house cool.Cooking utensils are darkening at the bottom and polished in the upper surface. The blacking surface will allow the heat while the silver surface won’t allow the heat to go out.EVALUATIONDefine the following terms A. conduction B. Convection C. RadiationState two application of radiation.Thermos FlaskA thermos flask is used to keep the temperature of its content constant. The essentialFeature of a thermos flask are as follows:Cork stopper – Prevent heat loss by conduction, conduction and EvaporationVacuum in the double wall – Reduce heat loss or gain by conduction and convectionSilvered wall surface – Minimize heat loss by radiationCork support – Prevent heat loss by conductionThermos flask is also known as vacuum flask.EVALUATIONDefine the following terms A. Conduction B. Convection C. RadiationWith the aid of a diagram, explain how the construction of a thermos flask minimizes heat exchange with the surroundingReading AssignmentNew School Physics pg 46 – 53WEEKEND ASSIGNMENTThe silver surface of a thermos flask minimizes heat loss by A. conduction B. radiation C. convection D. evaporationIs it advisable to wear a dark shirt in the tropical sun? A. yes it is B. No it is not C. Cannot say D. All of the aboveThe following are good conductors of heat except A. steel B. aluminum C. copper D. woolThe thermal conductivity of copper is greater than lead A. true B. false C. cannot say D. none of the aboveA stone floor feels warm to the feet but a rug or a carpet on the same floor feels cold A. true B. false C. cannot say D. none of the above THEORYDefine the following terms A. Conduction B. Convection C. Radiation.With the aid of a diagram, explain how the construction of a thermos flask minimizes heat exchange with the surrounding. WEEK SIXTOPIC: ELECTRIC CHARGES→ Production, Types, Distribution and StorageCONTENTProduction of ChargesTypes of ChargesDistribution of ChargesStorage of ChargesProduction of ChargesIf a plastic pen is rub vigorously on the hair or on a coat and it is hold near a very small piece of paper, the paper will be attracted by the pen. Some substances are found to poses the ability to attract light objects once they are rubbed. The light object as well as the rubbed material are said to be charged or electrified with static electricity.Electrostatics is the study of charges at rest. It is a type of electricity that does not move from one point to another in the substance in which it is produced.Types of ChargesThere are two types of charges – positive and negative charges.Positive charge is obtained when a glass rod is rubbed with silk, or cellulose acetate with silk, while negative charge is obtained when an ebonite rod is rubbed with fur or polythene with fur.These two rods with positive and negative electrification attract each other when brought close. Repulsion occurs if two similar rods are brought close.FUNDAMENTAL LAW OF ELECTROSTATICSThe law states that like charges repel, unlike charges attract.CONDUCTORS AND INSULATORSConductors are materials that allow electrons to pass through them easily. Examples of conductors are metals, damp air, graphite, acids, salt solutions, the earth, and the human body.Insulators are materials that do not allow electrons to pass through them easily. Examples of insulators are plastic, polythene, Bakelite, ebonite, paper, dry hair, silk, oils, glass, sulphur and wood.EVALUATIONState the fundamental law of electrostatic.What is electrostatic?Distribution of ChargesExperimental works have shown that charges are distributed where there is a sharp curve. The densities of these charges are greater at the surface of sharp curve. The charge per unit area of a charged surface is called surface density.Fig. 2.3 Charge Distribution is greater at the edge (sharp edge)Storage of ChargesThe electrophorus is a device for transferring and storing charges. It produces electric charges by electrostatic induction. Another device for the storage of electric charges is the capacitorEVALUATIONWith the aid of a diagram, explain charge distribution.Name two devices that can store charge.Reading AssignmentNew School Physics pg 56 – 58, 63 – 65WEEKEND ASSIGNMENTElectophorus and capacitor can store charges A. true B. false C. cannot say D. none of the aboveWhen an ebonite rod is rub with fur, the fur becomes A. positively charge B. negatively charge C. neutral D. none of the aboveThe ebonite rod in question 2 becomes A. positively charge B. negatively charge C. neutral D. none of the aboveLike charges A. attract B. repel C. disappear D. evaporateCharges are unusually concentrated at places where the surface is …………. A. straight B. sharply curved C. oval in shape D. none of the aboveTHEORYState the fundamental law of electrostatic.What is electrostatic?WEEK SEVENTOPIC: Gold Leaf Electroscope and Its Uses. Lighting and Lighting Conductor.CONTENTGold Leaf ElectroscopeLighting and Lighting Conductor.Gold Leaf ElectroscopeThe gold-leaf electroscope is an instrument used for testing positive and negative charges. It consists of a metal (brass) rod to which a thin gold-leaf (or aluminium leaf) is attached. The rod is surmounted by a brass disc or cap and insulated from the metal case. The leaf is protected from outside influences (like drought) by enclosing it in an earthed metal case with glass windows.Generally, the gold-leaf can also be used to test the conducting properties of materials.Fig. 2.1 Gold-leaf electroscopeUses of ElectroscopeIt is used to test whether a material is a conductor or an insulator. The material is made to touch the cap. Rapid collapse means that the charges escape easily and hence the material concerned is a good conductor. A slow collapse means that it is a poor conductor. No collapse means that it is an insulator.Use to test charges whether the charge is positive or negative. The gold leave electroscope to test the sign of the charge of an object. If an unknown charge is brought near to a charged electroscope and the leaf diverges more, the unknown charge is similar to the charge on the electroscope.CHARGING AN INSULATED BODYA neutral insulated body can be charged by two methodsContact method andBy inductionContact Method: - The method is achieved by bringing a charged object in contact with it. By so doing the neutral insulated body acquired the same type of charge as that on the charged object.Induction Method: - This method is simply a process of charging a neutral body by placing a charged body near it without any contact between the two.This process is as explained in the following steps below:Bring a positive charge close to an insulated body to be charged. (Note: insulation as used here is by placing body on an insulated stand to avoid the charge induced from leaking away). Negative charges on insulated body are attracted towards the inducing charge while the positive charges are repelled away from it.Earth the insulated body by momentarily touching it so that the positive charge conducts away(ii)(i) (iii)Fig. 2.2 charging by inductionRemove inducing charge: From observation, the negative charge will spread round leaving the body is a negatively charged body. If the inducing charge is negative, then the body will acquire a negative charge after taking the steps above.EVALUATIONState two uses of an electroscope.Draw a well label diagram of an electroscope.Lighting and Lighting ConductorThe atmosphere is known to contain ions or charged particles, which have been produced by radiation from the sun and by what is known as cosmic radiation, which enters the atmosphere from outer space.Lighting is a sudden discharge or neutralizing of electric charges, and it occurs when charges build up in a cloud.The lighting conductors are long metal strips running from the spike end of a conductor on the top of a building. They are used to prevent building from destruction when struck by thunder or lightning. The conductor is a long metal rod installed or connected to the earth by means of a cable. The sharp outer point of the top gains an induced charge opposite to that in the thundercloud. The charge ionizes the nearby air and the charged air molecules flow upwards from the point. This discharges the cloud before a lightning flash occurs.EVALUATIONWhat is the function of lighting conductors?Define lighting.Reading AssignmentNew School Physics pg 58 -63WEEKEND ASSIGNMENT……………… is a device use to detect charge A. Electrophorus B. Capacitor C. Electroscope D. InductorA lighting conductor is used to protect a building from lighting damage. A. true B. false C. cannot say D. none of the above…………… is the sensitive part of an electroscope A. The casing B. The cap C. The gold leaf D. The brass rodThe casing of an electroscope is earthed so as to screen the leaf from outside interference A. positively charge B. negatively charge C. neutral D. none of the aboveCapacitor is a device that …………. charges A. produces B. emits C. store D. none of the above THEORYExplain the two uses of an electroscope.Draw a well label diagram of an electroscope.WEEK 8TOPIC: FIELD – CONCEPT AND TYPES OF FIELD. GRAVITATIONAL AND MAGNETIC FIELD. FORCE OF GRAVITYCONTENTConcept of FieldTypes of FieldGravitational FieldConcept of FieldField can be defined as the region or space under the influence of some physical agency such as gravitational, electricity and magnetism.Types of FieldFields are of various types namely: gravitational, magnetic and electric field.Gravitational FieldGravitational field is any region or space around a mass in which the gravitational force of the mass is felt.If we throw up massive objects, it is our common observation that they move up to their highest points, stay stationary very briefly and eventually move downwards, falling faster and faster until they hit the ground level. The up and down movements objects on the earth’s surface are subject to the influence of the gravitational field.Force of GravityThe force of gravity is the pull of attraction between the earth, itself and objects on or near it.Newton’s Law of Universal GravitationNewton’s law of gravitation states that the force of attraction between two bodies of mass M1 and M2 is inversely proportional to the square of their distance R, between their centres and it is directly proportional to the product of their mass.Mathematical expression F α F = Where F is the gravitational force on either particle, M1 and M2 are their masses, R is the distance between them, and G is a universal gravitational constant, whose numerical value depends on the units in which the force, mass, and length are expressed.Acceleration Due to GravityThe acceleration of objects due to the earth’s gravitational attraction is called the acceleration due to gravity. It is represented by the symbol g whose average value is about 9.81ms−2.Without air resistance, different mass or objects released from rest at the same point will fall to the ground at the same time (free fall).EVALUATIONDefine field.State Newton’s law of gravitation. Magnetic FieldThe region or space around a magnet in which the influence of the magnet can be felt or detected is called a magnetic field. If a white sheet of paper is placed over a magnet and iron fillings are sprinkled on the paper, it will be observed that the iron filings will arrange themselves in a definite pattern which illustrates the magnetic lines of force of the magnet. A similar pattern can be obtained by using the compass needle to plot the magnetic lines of force.Fig 3.0 Magnetic Lines of Force Round a Bar MagnetLines of ForceA line of force is an imaginary line drawn in such a way that its direction at any point, that is the direction of the tangent, is the same as the direction of the field at that point.EVALUATIONDefine magnetic field.Define gravitational field. Reading AssignmentNew School Physics pg 67 - 70WEEKEND ASSIGNMENT (THEORY)Define A. gravitational field B. acceleration due to gravity. How does acceleration vary with latitudeA. Explain what is meant by a field as used in physics. B. Mention three types of field known to you WEEK NINETOPIC: Electric Field – Line of Forces, Properties of Line of Force, Description and Properties of Force FieldCONTENT Electric FieldLine of Force and properties Electric FieldElectric field is defined as any region where a charge experiences a force of electrical origin. There are two types of charges namely : positive and negative charges.Lines of ForceAn electric field has been defined as a region where an electric force is experienced. Electric fields can be mapped out by electrostatic lines of force. An electrostatic line of force may be defined as a line whose tangent is in the direction of the force on small positive charge at that point. Arrows on the lines of force show the direction of the force on a positive charge. The force on a negative charge is in the opposite direction.Since the direction of a field varies from point to point, lines of force are usually curves.Fig 4.1: Lines of Electrostatic force(i) Isolated positive charge (ii) Isolated negative charge (iii) Unlike charges – positive and negative charges (iv) like charges – positive and positive chargesProperties of Lines of Force1. Lines of force never intersect.2. Lines of force are usually curves, as the direction of a field varies from point to point.3. In a uniform field, the lines of force are straight, parallel and uniformly spaced.4. No lines of force originate or terminate in the space surrounding a charge.5. Every lines of force in an electrostatic field is a continuous line terminated by a positive charge at one end and a negative charge at the other end. Coloumb’s Law states that the force experience by two charges Q1Q2 separated by a distance r is directly proportional to their product of their charges and inversely proportional to the square of their distance apart. It is also known as inverse square law.Q1 Q2 F α Q1Q2Fα 1/r2F α Q1Q2 r² F = K Q1Q2 __________ (i) r² K = 9 x 109 Nm² C-2 ⁄ f/m K = 1 4ΩЄ0 (Permitivity of Free Space vacuum)EVALUATION State four properties of line of force.State coulomb’s law.Electric Field Intensity (E)It is simply the force per unit charge. It is a vector quantity and measured inE = F/Q _________ (iii)Electric Field Potential (V) It is the work done in moving a unit positive charge from it point of infinity to a point in the field. It can also be defined as work done per unit charge, it is a scalar quantity and measured in joules per coloumb or volt.V = W Q Flux Density D.It is denoted by D. It is simply charge by unit area. It is measured in Cm-2/ Clm² D = Q A EVALUATIONDefine A. electric field intensity B. electric field potentialDifferentiate between electric potential and electric potential energyReading AssignmentNew School Physics pg 72 & 73WEEKEND ASSIGNMENTThe SI unit of flux density is A. Cm2 B. Cm C. Cm-2 D. CElectric potential is a scalar quantity A. true B. false C. cannot say D. none of the aboveElectric field intensity is a scalar quantity A. true B. false C. cannot say D. none of the aboveThe SI unit of electric potential energy is ………. A. volt B. Joules per coulomb C. Joules D. Cm2 Line of force are maginary A. true B. false C. cannot say D. none of the aboveTHEORYThe force acting on an electron carrying a charge of 1.6X10-19 C in an electric field of intensity 5X108 Vm-1. 1f 20MJ of work is done in moving a 5µC of charge between two points in an electric field, the potential difference between the two points is?WEEK TENTOPIC: PRODUCTION OF CONTINUOUS ELECTRIC CURRENTCONTENTProduction of Continuous Current From Mechanical Energy.Production of Continuous Current From Chemical Energy Production of Continuous Current From Heat Energy Production of Continuous Current from Solar Energy.Production of continuous energy from mechanical energyWhen a force is applied at a prime mover, the prime mover drives the amature/ rotar. As the amature is rotating in the magnetic field system , the amature cuts the magnetic flux produce by the magnet. Hence E.M.F will be induced in the coil of the amature based on faraday’s law of electromagnetic induction.The induced E.M.F can be supplied to an external load.Production of Continuous Current from Chemical EnergyA cell consist of two dissimilar metals separated by solution of various acids or salt. The metal are known as the electrodes and the solutions are the electrolyte. The positive electrode is known as the anode. The negative electrode is the cathode.A cell is a device for converting chemical energy into electrical energy.EVALUATIONWith the aid of a diagram, describe how continuous current can be generated from mechanical energy.With the aid of a diagram, describe how continuous current can be generated from chemical energy.Production of Continuous Current from Heat EnergyThe ends of two dissimilar metal joined are inserted in cold and hot water and a galvamometer to detect the flow of charges. Due to temperature difference at both end current will flow in the connection. The greater the difference in temperature between the hot and cold junction, the greater the current flow.Production of Continuous Current from Solar EnergyIf solar energy is made to fall on a photo electric cell, solar energy will be converted to electric energy directly by photo electric effect.EVALUATIONWith the aid of a diagram, describe how continuous current can be generated from mechanical energy.With the aid of a diagram, describe how continuous current can be generated from chemical energy.Reading AssignmentNew School Physics pg 75 - 77WEEKEND ASSIGNMENT1. Cell convert chemical energy into ________ energy A. mechanical B. electricalC. solar D. atomic 2. DC generator convert A. electric to mechanical energy B. mechanical to electric energy C. solar to electrical energy D. none of the above3. Thermocouple consist of two A. similar metals B. dissimilar metals C. alloys metals D. none of the above.4. The feature that produces magnetic flux in a generator is ______ A. AmatureB. magnet C. stator D. prime mover5. Conversion of mechanical energy into electrical energy in a dc generator is base on what principle A. moment B. faraday’s law of electromagnetic induction C. coulomb’s law D. fundamental law of electrostatic. THEORYWith the aid of a diagram, describe how mechanical energy is converted to electrical energy.With the aid of a diagram, describe how heat energy is converted to electrical energy.
SENIOR SECONDARY SCHOOL 2TERM:SECONDSCHEME OF WORKWEEK TOPICHeat energy – temperature and its measurementHeat capacity and specific heat capacityCalculations on specific heat capacityEvaporation, boiling and melting points and their determination. Effects of impurities and pressure on boiling and meltingLatent heat – Fusion and vaporizationVapor pressure – Saturated and unsaturated vapor pressure and its relation to boiling. Humidity ,Relative Humidity, Dew point and its relationship to weatherMid-term projectGas Laws – Boyle’s, Charles’, Pressure and General gas lawProduction and propagation of wavesProperties of waves – reflection, refraction, diffraction, interference and polarizationLight waves – source, reflection, reflection plane and curved mirrorsRefraction of light – refractive index, its determination, total internal reflection and critical angleRevisionExaminationWEEK ONEHEAT ENERGYHeat TemperatureMeasurement of temperatureThermometersHeatHeat is a measure of total internal energy of a body. It is a form of energy due to a temperature difference. It is measured in Joule, JTemperatureTemperature is the degree of hotness or coldness of a body. The unit of temperature is in degree Celsius (0C) or Kelvin (K)Measurement of temperatureTemperature is measured by using thermometers. Thermometers have two reference temperatures or fixed points called the upper fixed point and lower fixed point.The upper fixed point is the temperature of steam from pure water boiling at standard atmospheric pressure of 760mm of mercury. It is 1000CThe lower fixed point is the temperature of pure melting ice at the standard atmospheric pressure of 760mm of mercury. It is 00CTemperature scalesThe difference in temperature between the upper and lower fixed points is called fundamental interval of a thermometer. The calibration of this interval depends on any of the three scales below:Celsius scaleFahrenheit scaleKelvin or Absolute scaleThe S. I. Unit of temperature is the Kelvin. However, it is also measured in degree Celsius and Fahrenheit.ThermometersThermometers are instruments used to measure temperature. Thermometers are named using the thermometric properties employed in the measurement of temperature. Each one makes use of the change in the physical properties of materials they are made of, to indicate temperature change.1. The liquid-in-glass thermometer: The liquid-in-glass thermometer depends on the uniform expansivity of the liquid used with temperature change. Any liquid that will be used as a thermometric liquid must be good conductor of heat, be easily seen in glass, have a high boiling point, have a low freezing point, have a low specific heat capacity, must not wet glass and must expand uniformly.2. The clinical thermometer: This has a constriction and it has a short range (350C – 430C). The narrow constriction prevents the mercury from flowing back into the bulb immediately after the thermometer has been removed from the patient’s body.3. Platinum resistance thermometer: This thermometer depends on the variation in the electrical resistance of a conductor with temperature as expressed below:The Thermocouple: A thermocouple consists of two different metals joined together by a circuit containing a galvanometer. The working of a thermocouple depends on the variation of the electromotive force (e.m.f) between junctions. The equation of the relationship is, where a, b and c are constantsConstant – volume gas thermometer: This depends on the variation in the pressure of a gas at constant volume with changes in the temperature of the gas.The equation is:ABSOLUTE SCALE OF TEMPERATURETemperature has no property of direction but has magnitude or size, which depends on the scale being used.The absolute scale of temperature is thermodynamic scale because it gives us the idea of the lowest possible temperature or absolute zero with the value of –2730K.The absolute zero is the lowest possible temperature below which nothing can be cooled since temperature is the measure of the average or mean kinetic energy of the molecules of a substance. It follows that as we subtract heat from a substance, its temperature drops and hence its kinetic energy until it eventually becomes zero under which the molecules remain stationary.The Celsius seal is the most commonly used scale. This scale is based on two fixed points – the lower fixed point (O0C) and the upper fixed point (1000C). The gap between these points is called the fundamental interval. 2120F 1000C 373K 320F 00C 273KFahrenheit scale Celsius scale Kelvin scaleTo convert from one scale to another, use interpolation technique. 2120F 1000C 373K F C K 320F 00C 273KFahrenheit scale Celsius scale Kelvin scaleWhere:F is the unknown in Fahrenheit scale;C is the unknown in the Celsius scaleK is the unknown in the Kelvin scaleThe formula below can be usedCLASSWORK 1Define (i) ice point (ii) steam pointGive five properties of thermometric liquidThe length of mercury thread when it is at 00C, 1000C and at an unknown temperature θ is 5mm, and 125mm respectively. Find the value of θASSIGNMENT 1SECTION AAn un-graduated thermometer reads 2.0cm and 112.0cm at ice and steam points respectively. Determine the true temperature in Kelvin, when the thermometer reads 5.0cm (a) 303.0K (b) 300.0K (c) 278.0K (d) 30.0K (e) 30.3KClinical thermometer differs from other mercury in glass thermometers because it has I. a constriction II. A wide range III. A short range IV. A narrow bore (a) I and II only (b) I and III only (c) III and IV only (d) I, II and III only (e) I, III and IV onlyA platinum resistance thermometer has a resistance of 4Ω at 00C and 12Ω at 1000C. Assuming that the resistance changes uniformly with temperature, calculate the resistance of the temperature when the temperature is 450C (a) 6.0Ω (b) 6.5Ω (c) 7.6Ω (d) 8.4Ω (e) 16.0ΩThe purpose of constriction in a clinical thermometer is to (a)prevent the mercury from expanding beyond the bulb (b) prevent the mercury from falling back into the bulb until required (c) enable the mercury to expand slowly (d) serve as the lower limit of the scale to be read (e) none of the aboveMercury has an advantage over other liquids as thermometric liquid because it (a) has low expansivity (b) has higher conductivity (c) vaporizes easily (d) relatively low freezing point (e) none of the above SECTION BWhat is temperature?Distinguish between temperature and heatGive three advantages of mercury over alcohol as a thermometric liquidThe pressure at ice point for a constant volume gas is 4.81×104Pa. while that of the steam point is 6.48×104Pa. what temperature will this thermometer indicate at 500CWEEKS TWO & THREEHEAT CAPACITY AND SPECIFIC HEAT CAPACITYHeat capacitySpecific heat capacityMEASUREMENT OF HEAT ENERGYIn order to assess the quantity of heat energy possessed by a body, three quantities are needed. They are:the change in temperature (θ)the specific heat capacity of the body (C)mass of the body (m)The quantity of heat Q of a body is a product of the three quantities above as expressed by the equation. …1It is measured in JoulesHeat capacityThis is the quantity of heat required to raise the temperature of a substance by one degree. It is measured in Joules/K. …2Specific heat capacitySpecific heat capacity of a substance is the heat required to raise the temperature of a unit mass of the substance through one degree change in temperatureThe quantity of heat Q received by a body is proportional to its mass (m), and temperature change and on the nature of the material the body is made of.Thus; …3 …4C is a constant of proportionality called the specific heat capacity of the body, which depends on the nature of the body. …5The unit of specific heat capacity is It can be determined by using the method of mixturesthe electrical methodDETERMINATION OF SPECIFIC HEAT CAPACITY BY MIXTURE METHOD The solid lead block is weighed on a balance to be Ms. A lagged calorimeter is dried and weighed to be Mc. It is then reweighed to be Mcw when half filled with water. The initial temperature of the water is taken to be θ1.The lead block is suspended in boiling water with a temperature θ2 after which it is transferred to the calorimeter and the mixture stirred to maintain a uniform temperature θ3The specific heat capacity of the lead can be calculated using the fact that heat loss by the lead = heat gained by calorimeter and water.Given the specific heat capacity of calorimeter and water to be Cs, Cc and Cw respectivelyHeat loss by the lead = heat gained by calorimeter and water …6 …7DETERMINATION OF SPECIFIC HEAT CAPACITY BY ELECTRICAL METHODFor a solid:To calculate the specific heat capacity Cb of a solid brass block, we make two holes in a weighed brass block into which a thermometer and a heating element connected to a source of power supply are inserted. Oil is poured in the holes to ensure thermal conductivity. Assuming no heat is lost to the surrounding, the total amount of electrical heat energy supplied by the coil is equal to heat gained by the brassHeat energy supplied by the coil = Heat gained by the brass …8From ohms law, …9So equation 8, …10 …11For a liquid …12CALCULATIONS ON SPECIFIC HEAT CAPACITYCalculations on specific heat capacityCalculations on specific heat capacityEXAMPLE250g of lead at 1700C is dropped into 100g of water at 00C. If the final steady temperature is 120C, calculate the specific heat capacity of lead. (Cw = 4.2 x 103 Jkg-1k-1)CLASSWORK 2 & 3Define is heat capacity?A metal of mass 0.5kg is heated to 1000C, transferred to a well lagged calorimeter of heat capacity 80 J/k containing water of heat capacity 420 J/k at 150C. If the final steady temperature of the mixture is 250C, find the specific heat capacity of the metalExplain the meaning of the statement, the specific heat capacity of a substance is 777JKg-1K-1ASSIGNMENT 2 & 3SECTION AA waterfall is 630m high. What is the change in temperature of a quantity of water that falls from the top to the bottom of the waterfall? [Neglect heat lost to the surroundings, take acceleration due to gravity as 10ms-2 and Specific capacity of water as 4200 JKg-1K-1] (a) 0.150C (b) 1.500C (c) 15.00C (d) 21.00C (e) 150.00CAn electric heater rated 12V is used to heat 450g of water when a current of 5A was passed through it. What is the final temperature after 30minutes? [Specific capacity of water = 4200 JKg-1K-1] (a) 57k (b) 20k (c) 57k (d) 80k (e) 40kIf 60g of water at 900C is poured into a calorimeter containing 20g of water at 300C, calculate the final steady temperature of the mixture (a) 900C (b) 750C (c) 680C (d) 250C (e) 1010CHow much heat is required to change 10kg of an object from 20OC to 70OC? [Specific heat capacity of the object is 200JKg-1K-1](a) 1x105J (b) 1x104J (c) 40J (d) 105J (e) 40x105JWhich of the following is not used to determine the heat content of a body? (a) mass of the body (b) volume of the body (c) specific heat capacity of the body (d) temperature of the body (e) all of the aboveSECTION BA piece of copper of mass 120g is heated in an enclosure to a temperature of 1250C. It is then taken and held in the air for 30 seconds and dropped carefully into a copper calorimeter of mass 105g containing 200g of water at 200C. The temperature of the water rises to 250C. Calculate the rate at which heat is being lost from the copper when it is held in the air. [Specific heat capacity of copper = 400 JKg-1K-1, Specific capacity of water = 4200 JKg-1K-1]An immersion heater supplies heat at the rate of 500Js-1 (i) what is quantity of heat produced in 24 minutes (ii) if there is no heat loss, calculate the rise in temperature if a brass of 3kg initially at 300C absorbed all the heat produced by the heaterWEEK FOUREvaporationBoiling points Melting pointsEffects of impurities and pressure on boiling and meltingEvaporationEvaporation is defined as the process by which liquid molecules breaks away from the surface of the liquid to remain as vapor. It can also be simply defined as the process by which liquid changes to gas or vapor. Boiling pointAs heat is being added to a liquid, its temperature increases steadily until at a certain temperature when rapid evaporation is seen to occur in every parts of the liquid with the bubbles of vapor escaping to the surface. This process is known boiling.As a matter of distinction, evaporation occurs only at the surface of the liquid while boiling occurs throughout the entire mass of the liquid. Also evaporation takes place at all temperature but boiling occurs at a particular temperature called boiling point.Effects of pressure on boilingAn increase in pressure at the surface of a liquid of a liquid raises the boiling point of the liquid and conversely, a decrease in pressure lowers the boiling point of the liquid.Effects of impurities on boilingThe presence of impurities or of dissolved substances in a liquid raises the boiling point of the liquid but lowers the freezing pointMelting pointsMelting point is a temperature at which a solid substance has its bond broken such that it now flows as liquid. It is also defined as the constant temperature at which a substance changes state from solid to liquid. On the reverse, the constant temperature at which a substance changes state from liquid to solid is called freezing pointAPPLICATION IN PRESSURE COOKERThe fact that increased pressure raises the boiling point is put into a useful application in the pressure cooker. The increased pressure of the trapped gas above the liquid raises the boiling of the liquid inside the cooker. This provides a high cooking temperature needed to conserve fuel and save time.APPLICATION IN REFRIGERATORSRefrigerators make use of the cooling effect of evaporation. The volatile liquid such as liquid ammonia or Freon evaporates inside copper coil surrounding the freezing compartment, supported by electric pump which reduced the pressure. As the volatile liquid evaporates in those coils, it absorb heat from the surround air, consequently and cooling the inside of the refrigerator and its content.The vapor produced is pumped off into the condenser, where it is compressed by the pump and condenses back to liquid. The latent heat given out during this condensation is quickly dissipated by an arrangement of cooling fins at the back of refrigerator.Heat is eliminated by convection and radiation to the surroundings and by conduction into fins. The liquid is again passed into the evaporator coil and thus the level of cooling is regulated by a thermostat connected to the switch.CLASSWORK 4Define evaporationWhat is boiling?Differentiate between boiling and evaporationASSIGNMENT 4SECTION AA phenomenon which is used to describe the process by which a substance changes from solid to gas is called (a) evaporation (b) freezing (c) sublimation (d) melting (e) vaporizationWhat effect will reducing the surface pressure of a liquid have on its boiling point? (a) increase its boiling point (b) reduces its boiling point (c) it does not have effect (d) increases its boiling point by 50C (e) none of the aboveWhich of the following statement is true about evaporation (a) evaporation occurs at all temperature except at boiling points (b) evaporation only occurs at boiling point (c) evaporation occurs at all temperature (d) all of the above (e) none of the aboveImpurities change the boiling points of liquid. So, salt added to water will (a) increase its boiling point (b) reduces its boiling point (c) it does not have effect (d) reduces its boiling point by 50C(e) none of the aboveWhich of the following statement is true for an ice if the pressure is lowered? (a) the melting point is increased (b) the boiling point is unchanged (c) the melting point is lowered (d) the melting point is unchanged (e) none of the aboveSECTION BWrite the effect of impurities and pressure changes on melting, freezing and boilingDescribe an experiment to determine the boiling point of a liquidWEEK FIVELATENT HEATLatent heat of FusionLatent heat of vaporizationSometimes when heat energy is given to a substance, it does not increase its temperature, rather, it changes the state of the substance; such heat is referred to as latent heat. There are two types of latent heat:Latent heat of fusionLatent heat of vaporizationLatent heat of FusionLatent heat of fusion: This is the quantity of energy needed to change solid to liquid without any change in temperature.Latent heat of vaporizationLatent heat of vaporization: This is the amount of energy needed to change liquid to gases (vapor) or steam at constant temperature.SPECIFIC LATENT HEATThis is the quantity of heat required to change a unit mass of a substance from one state to another without a change in its temperature.(a) SPECIFIC LATENT HEAT OF FUSION (Lf)This is the quantity of heat required to change a unit mass of a solid to liquid without a change in its temperature. The specific latent heat of fusion of ice is 33600 J/kg. …1(b) SPECIFIC LATENT HEAT OF VAPORISATION (Lv)This is the quantity of heat required to convert a unit mass of liquid to vapor (gaseous state) without any change in temperature. For water the value is 2.26 x 106 J/kg …2EXAMPLE1. How much heat energy is needed to change 3g of ice at 00C to steam at 1000C? (Lf = 336 KJ/kg, Cw = 4200 J/kgk, Lv = 2.26 x 106 J/kgFirst stage:Heat required for the ice to melt at 00CSecond Stage:Heat required to raise the temperature of the melted ice from 00C to 1000C Third Stage:Heat required to convert the liquid to steamThe total energy,CLASSWORK 5Differentiate between specific heat capacity and specific latent heatCalculate the total energy required to evaporate completely 1kg of ice that is initially at – 100C. Given that:[Specific capacity of Ice = 2.2 x 103 J/kgk, Specific heat that capacity of water = 4.2 x 103 J/kgk, Specific latent heat of fusion of Ice = 3.36 x 105 J/kg, Specific latent heat of vaporization = 2.26 x 106 J/kg]ASSIGNMENT 5SECTION A Determine the heat required to change 10g of ice at 0OC to water at 10OC if specific latent heat of ice is 335J/g and specific heat capacity of water is 4.2J/gk (a) 3.77 x 103J (b) 4.00 x 103J (c) 4.50 x 103J (d) 1.33x 103J (e) 4.9x 103JWhich of the following is the correct SI unit of specific latent heat? (a) Jkgk (b) Jkg-1k-1 (c) Jkgk-1 (d) Jkg-1 (e) JkgLatent heat of fusion changes substances from its (a) solid state to liquid state (b) from liquid to solid (c) from liquid to gasThe heat required to change 1kg of ice at 00C to water at the same temperature is called (a) specific latent heat of vaporization (b) specific heat capacity (c) specific latent heat of fusion (d) heat capacity (e) specific heat capacitySECTION BAn electric heater immersed in water of mass m, raised the temperature of the water from 400C to 1000C in 5.0 minutes. After another 11.25minutes, one-quarter of the water has been converted to steam. Calculate the specific latent heat of vaporization of water. [Specific heat capacity of water = 4200 Jkg-1K-1] Calculate the energy required to vaporize 50g of water initially at 800C. [Specific heat capacity of water = 4.2Jg-1K-1; specific latent heat of vaporization of water = 2260 Jg-1] WEEK SIXVAPOUR PRESSURESaturated and unsaturated vapor pressure and its relation to boilingHumidityRelative HumidityDew point and its relationship weatherVapor PressureWhen a liquid evaporates in a closed container, the vapor formed above the liquid exerts a pressure. According to kinetic molecular theory, the molecules of the vapor are in constant motion and will hence exert a pressure just like the molecules of a gas. This pressure is called the vapor pressure of the liquid.Saturated and unsaturated vapor pressure and its relation to boilingA saturated vapor is a vapor that is in contact with its own liquid within a confined space. When the enclosed space above a liquid is saturated with vapor molecules and can hold no more molecules, the pressure exerted by this saturated vapor is said to be the saturated vapor pressure (s. v. p) of the liquid. The vapor is said to be saturated when the number of molecules escaping from the liquid per unit is equal to the number returning to the liquid per unit time. The saturated vapor is thus said to be in a state of dynamic equilibrium with its own liquid. Saturated vapor pressure increases with temperature.On the other hand, the unsaturated vapor is the vapor which is not in contact with its own liquid in a confine space. It is not in dynamic equilibrium with its own liquid. The rate at which the liquid evaporates is greater than the rate at which the liquid condenses. Thus, the pressure exerted by a vapor which is not in contact with its own liquid in a confined space is called unsaturated vapor pressure.HumidityHumidity is the measure of wetness of the atmosphere. The exact amount of water vapor in the atmosphere at a given temperature is called absolute humidity. At higher temperature, the atmosphere contains more water vapor compared to water vapor present at low temperature.Relative HumidityRelative humidity is defined as the ratio of the mass of water vapor per unit volume present in the atmosphere to the mass per unit volume of the water vapor needed to saturate the atmosphere.An instrument known as the hygrometer is used to measure relative humidity of air.Dew point and its relationship to weatherDew point is the temperature at which the water vapors present in the air just sufficient to saturate it. It is also defined as the temperature at which the pressure of the water is vapor is equal to the saturation vapor pressure.Mist – mist occur in wet air with high relative humidity above 75 when water vapor in the air is cooled below its dew point. Mist limits visibility to about 1000m or less.Fog – fog is formed when water vapor in the air is cooled down to its dew point. Fog is of more effect than the mist as it can reduce visibility to less than 200m.CLASSWORK 6Define vapor pressureDifferentiate between saturated and unsaturated vapor pressureASSIGNMENT 6SECTION AThe temperature at which the saturated vapor pressure of a liquid is equal to the atmospheric pressure gives rise to a phenomenon called (a) boiling point (b) melting point (c) evaporation (d) freezing point (e) no answerThe instrument used to measure relative humidity of an environment is (a) hydrometer (b) hygrometer (c) humid-meter (d) hygroscope (e) none of the above Which of these statements is/are correct? (i) the atmosphere above is cooler than the ones below (ii) for unsaturated vapor, the rate at which the liquid evaporates is greater than the rate at which the liquid condenses (iii) mist is of lesser weather effect than fog (a) all of the above (b) (i) and (ii) only (c) (i) and (iii) only (d) (ii) and (iii) only (e) none of the aboveWhich of these is true of saturated vapor pressure? (i) saturated vapor pressure of a liquid increases with temperature (ii) saturated vapor pressure of a liquid does not have contact with the liquid (iii) saturated vapor pressure is in a state of dynamic equilibrium with its own liquid (a) all of the above (b) (i) and (ii) only (c) (i) and (iii) only (d) (ii) and (iii) only (e) none of the aboveThe temperature at which the water vapors present in the air just sufficient to saturate it is referred to as (a) relative humidity (b) vaporization (c) dew point (d) condensation point (e) no answerSECTION BExplain the following terms: (i) Dew point (ii) Fog (iii) MistWrite short note on these: (i) humidity (ii) pressureDifferentiate between mist and fogMid-term projectUsing a white card board, draw the diagrammatic set up of determining the specific heat capacity of a solid substanceWEEK SEVENGAS LAWSBoyle’s LawCharles’ LawPressure LawGeneral gas LawIn an attempt to study the behavior of gases in relation to volume, temperature and pressure, the following conditions are investigatedvariation of volume with pressure at constant temperature, Boyle’s law variation of volume with temperature at constant pressure, Charles law variation of pressure with temperature at constant volume, pressure law Boyle’s LawBoyle’s law states that the pressure of a fixed mass of gas varies inversely as the volume at constant temperature. ---1 ---2 ---3 ---4Charles’ LawCharles law states that for a fixed mass of gas at constant pressure, the volume is proportional to its absolute temperature ---5 ---6 ---7Pressure LawPressure law states that the pressure of a fixed mass of gas at constant volume is proportional to its absolute temperature. ---8 ---9Absolute Zero of TemperatureWhen the graphs of volume – temperature or pressure – temperature are extrapolated backwards they cut the temperature axis at -2730C. This temperature is called absolute zero, the temperature at which the volume of the gas theoretically becomes zero as it is being cooled. At his temperature, molecules of gas stop moving completely. This temperature is a mere assumption, as gases are known to liquefy more often than not before such a temperature is reached.General gas LawThe general gas law is the combination of the Boyle’s, Charles and Pressure Law.It follows thatFrom Boyle’s law From Charles’ lawFrom Gay-Lussac’s or Pressure lawIn combination, we have ---11 ---12Equation 12 is known as general gas law or relation. This can be written in the form: ---13Where: n=number of moles of gas R=the universal molar gas constant = 8.31JK-1 CLASSWORK 7State these laws and write its mathematical expressionCharles’ lawBoyle’s lawA vessel is filled with a gas at a temperature 500C and a pressure of 76cmHg. Calculate the final pressure if the volume of the gas is doubled while it is heated to 900CASSIGNMENT 7SECTION AThe equation PxVyTz = constant is Boyle’s law if (a) x=0, y=0, z=1 (b) x=1, y=0, z=0 (c) x=1, y=1, z=0 (d) x=1, y=1, z=1 (e) x=1, y=1, z=-1A column of air 10cm long is trapped in a tube at 270C. What is the length of the volume at 1000C? (a) 12.4cm (b) 13.7cm (c) 18.5cm (d) 37.0cm (e) 100cmThe volume of certain quantity of gas at 270C is 1200cm3. Calculate its volume at 1270C if the pressure remains constant. (a) 300cm3 (b) 400cm3 (c) 1000cm3 (d) 1600cm3 (e) 250cm3A fixed mass of gas of volume 600cm3 at a temperature of 270C is cooled at constant pressure to a temperature of 00C. What is the change in volume? (a) 54cm3 (b) 273cm3 (c) 300cm3 (d) 546cm3 (e) 600cm3A mass of gas occupies 20cm3 at 50C and 760mmHg pressure. What is its volume at 300C and 800mmHg pressure? (a) 41.4cm3 (b) 20.7cm3 (c) 50cm3 (d) 0.4cm3 (e) 25cm3SECTION B(a) State the ideal gas equation (b) Draw graphs to show Boyle’s law and Charles law(a) What is meant by absolute zero of temperature? (b) State the assumptions of the kinetic molecular theory of gases.WEEK EIGHTWAVESProduction of wavesPropagation of wavesWAVESA wave is a disturbance which travels through a medium transferring energy from one point to another without causing any permanent displacement of the mediumA wave motion is process of transferring a disturbance from one point to another without any transfer of particles of the medium.Types of wavesWaves are broadly classified into two typesBased on the medium of propagation: mechanical wave and electromagnetic waveBased on the comparison of the wave direction with the direction of vibration of the particle: transverse wave and longitudinal waveProduction and Propagation of waves: Based on the medium of propagationProduction and propagation of mechanical wavesA mechanical wave is the wave that requires material medium for its mode of propagation (or for it to transfer energy away from the source). Examples are waves travelling through springs, water waves, and sound wavesProduction and propagation of electromagnetic wavesElectromagnetic waves are waves that do not need material medium for its mode of propagation (or for it to transfer energy away from the source). Examples are radio waves, visible light, ultra-violet rays, x-rays, gamma rays. Electromagnetic waves travels at the speed of light (3.0×108m).A wave which travels along a medium transferring energy from one part of the medium to another is called a progressive wave. The progressive wave can be divided into transverse and longitudinal waves y Direction of wave motionProgressive or travelling waveA standing or stationary wave: this is formed when two waves travelling in the opposite direction meets or by superimposition of incident wave and its reflection. The amplitude of the standing wave varies along the wave. Incident wave reflected waveStanding or stationary waveProduction and Propagation of waves: Based on the comparison of the wave direction with the direction of vibration of the particleTransverse wavesA transverse wave is a wave in which travel perpendicularly to the direction of the vibrations producing the waves.Longitudinal waveLongitudinal waves are waves which travel in a direction parallel to the vibrations of the medium.TERMS USED IN DESCRIBING WAVESPhase - particles which are at the same vertical direction from their positions of rest and are moving in the same direction are said to be in phase.Cycle - is a complete to-and-fro movement or oscillation of a vibrating particleThe amplitude (A) - is the maximum displacement of a particle from its rest or mean position. It is measured in meter (m).The period (T) - is the time required for a particle to perform one complete cycle or oscillation ---1 ---2Frequency (f) - is the number of complete cycles made in one seconds. It is measured in Hertz (Hz)Wavelength (λ) - is the distance covered by the waves after one complete oscillation. For transverse waves, it is the distance between successive crests or troughs while for longitudinal wave, it is the distance between successive compressions or rarefactions. It is measured in meter (m).Wave-velocity (v) is the distance traveled by the waves in one second. The S.I unit is m/sDisplacement Crest complete oscillation or one cycle Amplitude Distance(x) Trough One wavelengthMATHEMATICAL RELATIONSHIP ---3 ---4From equation 1, We have: ---5 ---6 ---7Worked exampleA radio station broadcasts at frequency of 300 KHz. If the speed of the wave is 3 x 108 ms-1, calculate the period and wavelength of the wave? Mathematical representation of wave motion – Progressive waveThe general equation for stationary wave is given by: ---8Where A PO Φ π 2π t x λConsidering O and P that are out of phase by Φ, then we have ---8Where: ---9 ---10But ---11Substituting equation 11 into equation 8 gives: ---12 ---13Also from equation 12, putting we can have ---14Recall that Thus, equation 12 can be re-written as: ---15Example: A plane progressive wave is given by the equation Calculate: (i) The wavelength of the wave (ii) The speed (iii) The frequency (iv) The periodSolution:By comparing the given equation with the standard equation We have for: (i) The wavelength of the wave 2ft=2000tf=1000Hz(ii) The speed λ=2π×2λ=12.57m(iii) The frequencyv=f λv=1000 × 12.57v=12570m/s(iv) The periodt=10-3s-1CLASSWORK 8What is wave?Elias radio station broadcasts at a frequency of 21MHz. If the speed of light in the air 3×108ms-1, calculate the wavelength of the broadcast. Define stationary waveASSIGNMENT 8SECTION AAn electromagnetic radiation has a speed of 3×108ms-1 and a frequency of 106Hz, calculate its wavelength (a) 3.3×103m (b) 3.0×102m (c) 3.0×10-2m (d) 3.3×108m (e) 3.3×10-3mA body oscillates in simple harmonic motion according to the equation where x is expressed in meters. What does 0.05 represents? (a) velocity (b) frequency (c) period (d) amplitude (e) none of the aboveWhich of the following is not a mechanical wave (a) wave propagated in stretched string (b) waves in a closed pipe (c) radio waves (d) water waves (e) sound wavesThe maximum displacement of particles of wave from their equilibrium positions is called (a) wave velocity (b) period (c) amplitude (d) wavelength (e) frequencyD(cm)0 0.05 0.10 0.15 0.20 0.25 t(s)The diagram above represents the displacement D versus t graph of a progressive wave. Deduce the frequency of the wave(a) 20Hz (b) 10 Hz (c) 5 Hz (d) 4 Hz (e) 50 HzSECTION B(a) What is wave motion?(b) The equation represents a wave train in which y is the vertical displacement of a particle at a distance x from the origin in the medium through which the wave travelling. Explain, with the aid of a diagram, what A and λ represents.A radio waves transmitted from a certain radio station is represented by the wave equation: Calculate the (i) wavelength of the wave (ii) frequency of the wave (ii) velocity of the wave. Where x, y are in meters while t is in secondsWEEK NINEPROPERTIES OF WAVESReflectionRefractionDiffractionInterferencePolarizationPROPERTIES OF WAVESAll waves exhibit the following propertiesReflectionRefractionDiffractionInterferenceApart from the properties listed above transverse waves has another properties called polarization.ReflectionThis is a property of wave which occurs when a travelling wave strikes a surface and it bounces back. The travelling wave is the incident wave while the one that bounces back is the reflected rain. In case of water waves generated in a ripple tank, if the waves were made to incident normally on a plane strip, the wave will be reflected back along their original course.If the waves are incident at a particular angle, it will be observed that the angle of incidence is equal to the angle of reflection in line with the laws of reflectionReflected waveNormal r iIncident waveReflection of plane parallel wave from a plane surfaceLAWS OF REFLECTIONThe incident ray, the reflected ray and the normal, at point of incidence, all lie on the same plane.The angle of incidences is equal to the angle of reflectionRefractionThis is the change in the speed and direction of waves as it passes from one medium to another.When plane waves pass from deep to shallow water, their wavelength becomes shorter and thereby travels slowly. A change in the wavelength and speed produce a change in the direction of travel of waves when they cross the boundary. It is important to note that during refraction, the wavelength remains constant.Refractive index is the ratio of the sine of the incident angle (i) to the sine of the angle of refraction (r). It is also the ratio of the velocity of the wave in the first medium (v1) to the velocity in the second medium (v2)DiffractionThis is the spreading out of a wave on passing through a narrow opening. If waves are directed towards a large gap compared with the wavelength of the waves, slightly bent or beam of waves are formed on passing through the gap.If the barriers are placed closer to leave a narrow gap waves forms spherical wave fronts on passing through a narrow shit.Diffraction occurs when the wavelength of the wave is longer than the width of the opening or the size of the obstacles.InterferenceThis is a phenomenon which occurs when two similar waves traveling in the same direction cross each other. If the waves are in phase or step so that they travel the same distance at equal time and the crest or trough of the two waves arrive simultaneously or one is a complete wavelength ahead of the other. The resulting wave will build up to twice the amplitude of the two waves; this is called constructive or additive interference.If the crest of one wave arrives with the troughs of the waves, and vice-versa, the waves cancel each other out to give zero resultant, this is called destructive interference.PolarizationThis is an exclusive property of transverse waves only. It is the production of transverse vibration in only one plane. A transverse wave which vibrates in only one plane is said to be plane-polarized.Polarized light can be produced by passing an ordinary light through a polarizer called Polaroid or crystal of calcite, tourmaline or quartz. The arrangement of molecules within this polarizer will only permit the passage of light in a particular plane and then absorb light due to other vibration. Thus, when an unpolarized light is passed through a polarizer, the emergent light consists in only one plane.Application of PolaroidThe Polaroid is used in sunglasses to reduce the intensity of incident light and to eliminate reflected light glare.CLASSWORK 9(a) List the properties of waves that you know(b) Explain any twoDefine and explain the types of interferenceASSIGNMENT 9SECTTION AWhen a wave travels from air to water medium (a) the speed reduces (b) the speed increases (c) reflection occurs (d) all of the above (e) none of the aboveThe phenomenon which occurs when two similar waves traveling in the same direction cross each other (a) reflection (b) diffraction (c) refraction (d) polarization (e) interferenceWater waves are generated by dropping a stone into a calm pool of water. If a small piece of cork is floating in the path of the waves, the cork, as the wave progresses, will (a) sink into the water (b) move up and down about the same position (c) move toward the center of the pool (d) move along with the waves toward the bank of the pool (e) none of the aboveSurface waves travelling in deep water at 15ms-1 are incident at a shallow water boundary. If the angles of incidence and refraction are 450and 300 respectively, calculate the speed of the waves in the shallow water (a) 8.1 ms-1 (b) 10.0 ms-1 (c) 10.6 ms-1 (d) 22.5 ms-1 (e) 15ms-1Which of the following is an exclusive property of transverse waves only (a) reflection (b) diffraction (c) refraction (d) polarization (e) interferenceSECTION BWhat is polarization? State three uses of a PolaroidDifferentiate between reflection and refractionWEEK TENLIGHT WAVESLight waves Source of Light wavesReflection of Light wavesReflection of plane and curved mirrorsLight waves Light wave is a visible source of energy. It is also a wave motion. It has a very short wavelength of 5×10-4mm. Light travels at a speed of 3.0×108ms-1 Source of Light wavesThere are various sources of light: natural and artificial, luminous and non-luminous. Natural sources of light include the sun and the stars. Artificial sources of light are the candle, electric torch, the electric lamp, incandescent, arc light and fluorescent light.Self-luminous or luminous sources of light are those that generate and emit light by themselves e. g. the sun, stars, fire flies and some deep sea fishes Non-luminous objects are seen when they reflect or throw back light from a luminous objects. Examples of non-luminous objects are moon, paper, mirror, wall etc.When light falls on such surface, it is may be absorbed, transmitted or reflected, sometimes a combination of the above processes may occurLight rays and beamsA ray is the direction of the path in which light is travelling. It is represented by a straight-line with an arrowhead A light rayA beam is a collection of two or more rays of light. Beams can be parallel, convergent or divergent.A parallel beam is two or more rays travelling in the same direction but can never intersect each other. A parallel beamA beam of light is said to be convergent when they meet at a point A convergent beamThe divergent beam occurs when a collection of light rays has the same source is spread out apart. A divergent beamRECTILINEAR PROPAGATION OF LIGHTThe phenomenon of light travelling in straight line is known as rectilinear propagation of light. It can be demonstrated by placing a candle flame at the end of a straight pipe, light of the flame will be seen clearly at the other side of the pipe. If the pipe is then bent and the process repeated, nothing will be seen at the other end, this clearly shows that light travels in straight line. Two natural effects that result from the rectilinear propagation of light are the formation of eclipse and shadow, The principle of operation of the pin hole camera also depends on the fact that light travels in straight lines.SHADOWA shadow is an area in which light rays from a source cannot reach. It is produced by the obstruction of light by an opaque object. There are two types of shadow: partial (penumbra) shadow and total (umbra) shadow. If the light source is large, the shadow formed consist of two parts, a completely dark area known as umbra and an outer grey area known as penumbra or partial shadow. In the umbra region, the light from the source is completely blocked by the opaque body. In the penumbra region, the light is partially blocked by the opaque object. The inner region of the shadow receives less than the outer parts. Thus the penumbra becomes brighter from the umbra and outwards. ECLIPSEAn eclipse is a result of a shadow cast by one heavenly body on another. The sun being a luminous body and it is in the middle while the earth and the moon revolves round the sun. If the moon is between the sun and the earth, the shadow of the moon will be cast on the earth’s surface.There are two types of the eclipse. Viz:Eclipse of the sun (solar eclipse): here the moon comes between the sun and the earth in a straight lineEclipse of the moon (lunar) eclipse: in this case, the earth comes in between the sun and the moon.PIN HOLE CAMERAIt consists of a light proof box, one end of which has a small hole made with a pin or needle point. The opposite end has a screen made with tracing paper or ground glass. Light from an object in front of the pinhole passes through it and form an image on the screen. If the screen is replaced with a photographic paper or film, a picture of the object can be taken with the pinhole camera. When using the pinhole camera to take pictures of an object, long exposure is necessary to allow sufficient light to enter the box through the pin hole. The image formed on the screen of the pinhole camera will be seen more clearly if external light is excluded by covering head and camera with a dark cloth.The image formed on the screen of the pinhole camera is invertedLinear magnificationMagnification is defined as the ratio of the size (or height) of the image to the size (or height) of the object ---1 ---2Reflection of Light wavesReflection is the bouncing back of light waves when it strikes a surface.Reflection of plane mirrorsThere are two types of reflection:1. Regular Reflection2. Diffuse Reflection or Irregular ReflectionIn regular reflection, parallel rays of light incident on a smooth or polished surface are reflected as parallel rays in one direction. Incident ReflectedRays Rays Regular reflectionIn diffused or irregular reflection, parallel rays of light incident on a rough or irregular surface are reflected in various directionsIncident Diffuse or scattered reflectionLAWS OF REFLECTIONThe first law of reflection states that the incident ray, the reflected ray and the normal at the point of incidence all lie on the same planeThe second law of reflection states that the angle of incidence (i) is equal to angle of reflection (r).IMAGE FORMATION BY A PLANE MIRRORCHARACTERISTICS OF IMAGE FORMED BY PLANE MIRROR1. It is the same size as the object2. It is virtual3. It is laterally inverted4. It is upright5. It is far behind the mirror as the object is in front of the mirrorIMAGEThere are two types of image:1. Real image2. Virtual imageA real image is one that can be caught on a screen. Light rays actually pass through real image. A virtual image is one that cannot be caught on a screen. It is one through which rays do not actually pass but which is nevertheless visible to the eye.LATERAL INVERSIONThe effect on plane mirror on objects placed in front of it whereby the appearance of the image looks like a reversal of the object is known as lateral inversionAM MAIMAGES FORMED BY INCLINED MIRRORWhen two mirrors are placed at an angle to each other, the number of images formed is given by: ---3 N = Number of imagesӨ = Angle of inclinationWhen Ө = 1800, the two mirrors will act as a single mirror and therefore formed only one image. When Ө = O, the two mirrors are parallel to each other and the image of object placed between them will be at infinity.EFFECT OF MIRROR ROTATION ON REFLECTED RAY-MIRRO GALVANOMETERIf the direction of an incident ray on a mirror is kept constant and the mirror is rotated through twice that angle. This fact is utilized in mirror galvanometer (to measure very small electric current) and in the navigator’s sextant.ExampleThe reflection of a narrow beam of light incident normally on a plane mirror falls on a metre rule parallel to the mirror and at a distance of 1m. Calculate the angle of rotation of the mirror if the reflected beam is displaced 21.26cm along the metre-rule when the mirror rotated.Angle ONP = 2 ӨTan 2 Ө = 21.26 100 = 0.2126 2 Ө = tan-1 (0.2126) 2 Ө = 120 Ө = 60USES OF PLANE MIRRORIt is used in periscopeIt is used in kaleidoscopeIt is used in sextantReflection of curved mirrorsCurved mirrors differ in size, shape and direction of their curvature. In respect of shape, we have spherical and parabolic mirrors. There are two types of spherical mirrors – concave and convex mirrorsConcave mirrors – the concave mirrors are hollowed-out toward the incident light like the inside surface of a spoon. It is also called a converging mirror. C F P principal axis Concave mirrorConvex mirrors – these mirrors bulge towards the incident light like he back of a spoon. Convergent mirrors are also referred to as divergent mirrors. C P F Convex mirrorTerms used with spherical mirrorsThe pole (p) – this is the midpoint of the spherical mirrorsThe aperture – this is the width or diameter of the mirror.The center of curvature (c) – this is the centre of the large sphere from which the spherical mirror is carved out.The radius of curvature (R) – this is the distance between the center of curvature and the pole of the mirror.The principal axis – this is the imaginary line passing through the pole (p) and the center of curvature (c)The principal focus (f) – this is the point on the principal axis where the incident rays converges (for concave mirrors) or appear to diverge (for convex mirror)Focal length (f) – this is the distance between the focus and the pole of the spherical mirror. It is always half of radius of curvature ---4 ---5Spherical aberrationThis is the phenomenon whereby a spherical mirror of wide aperture cannot bring all parallel rays to the same focus. In other to avoid this, spherical mirrors of small aperture are usually used. This is also why parabolic mirrors are used in place of spherical mirrors in searchlights and car headlamps.Construction of ray diagramsThe following tips are used in constructing ray diagramsLight rays parallel to principal axis are reflected through the focusA light ray passing through the center of the curvature is reflected back along the same path A light ray passing through the focus is reflected parallel to the principal axis.Light rays striking the mirror at the pole is reflected such that the angle of incidence is equal to the angle of reflectionCharacteristics of image formed by concave mirrorsObject before center of curvature: the image formed is:same size the objectbetween the center of curvature and the focusinvertedrealObject at the center of curvature: the image formed issame size the objectat the center of curvatureinvertedrealObject between the center of curvature and the focus: the image formed isMagnifiedBeyond the center of curvatureInvertedrealObject at focus: the image formed isFormed at infinityObject between focus and the pole: the image formed isMagnifiedBehind the mirrorVirtualErectObject at infinity: the image formed isDiminishedFormed at the focusRealInvertedCharacteristics of image formed by convex mirrorsThe image formed by a convex mirror is always virtual, erect and diminished in size; it is formed between the pole and the principal focus. This is unlike the case of the concave mirror which can produce either real or virtual images that may be inverted or erect, magnified or diminished in size according to the position of the object.Linear magnificationThis is defined as the ratio of the image size to the object size ---6Mirror formulaThe focal length, f, object distance, u, and the image distance, v, can be related using the formula below: ---7From equation 6, we can have: ---8 ---9Also, from equation 7, we can have: ---10 ---11 ---12Sign conventionThis is used to know and calculate by properly assigning sign to all the parameters used in mirrorThe new Cartesian – here, all the distances measure to the left of the mirror from the pole are negative while distances measured to the right of the mirror from the pole are positiveReal is positive and virtual is negative – this is the most widely accepted and used in calculations for mirrors and lenses. In this case:All distances are measured from the pole of the mirror to either left or rightThe distance of real objects and real images are positiveThe distance of virtual objects and virtual images are negativeThe focal length of a concave mirror is positive while the focal length of a convex mirror is negativeExampleAn object which is 5.0cm high is placed 10.0cm in front of a convex mirror of focal length 15.0cm. Find the position, size and nature of the image produced.SolutionUsing “real is positive”Given that f=-15cm, u=10cmFor magnificationThus, the image is formed 6.0cm behind the mirror and the height 3.0cm. it is erect, virtual, diminishedCLASSWORK 10(a) What do you understand by the term lateral inversion? (b) write your first name in block form to buttress (a)Differentiate between concave and convex mirrorTwo plane mirrors inclining at an unknown angle, forms 11 images. Find the value of the angleMention three uses of plane mirrorsASSIGNMENT 10SECTION AWhich of the following abatement is true of virtual image (a) it is formed on the screen (b) it is formed by the intersection of actual rays (c) rays of light do not pass through it (d) all of the above (e) none of the above An object is placed between two plane mirrors inclined at 600 to each other. How many images will the observer see? (a) 6 (b) 5 (c) 4 (d) 3 (e) 2An object is place 15cm in front of a concave mirror of focal length 20cm, the image formed is (a) real, inverted and diminished (b) real, inverted and magnified (c) virtual, erect and diminished (d) virtual, erect and magnified (e) virtual, inverted and magnifiedA concave mirror can be used to produce can be used to produce a parallel beam of light if a light bulb is placed (a) between its focus and the pole (b) at its focus (c) at its center of curvature (d) between its focus and the center of curvature (e) none of the aboveWhen an image is formed in a plane mirror, the image formed will be (a) the same size as the object (b) smaller than the object (c) laterally inverted (d) always virtual (e) all of the aboveUsing the real is positive sign convention determine the sign of the focal length of a convex mirror (a) positive (b) negative (c) neutral (d) none of the above (e) options (a) and (b)An object is placed in front of a concave mirror of radius of curvature 12cm. if the height of the real image formed is three times that of the object, calculate the distance of the object from the mirror (a) 24 cm (b) 16 cm (c) 12 cm (d) 8 cm (e) 4 cmA magnified erect image four times the size of the object is formed by a concave mirror of focal length 12cm. what is the distance of the image from the pole of the mirror? (a) -36cm (b) -18cm (c) -24cm (d) -3.6cm (e) 24cmA boy walks away from a plane mirror at a constant speed of 5.0ms-1 in a direction normal to the surface of the mirror. At what speed does his image move away from him? (a) 5.0ms-1 (b) 2.50ms-1 (c) 3.5.0ms-1 (d) 1.25.0ms-1 (e) 0.00ms-1The image of an object is located 6cm behind a convex mirror. if its magnification is 0.6, calculate the focal length of the mirror (a) 3.75 cm (b) 6.60 cm (c) 10.00 cm (d) 15.00 cm (e) 20.00 cmSECTION B(a) Give the differences between real and a virtual image(b) A magnified, virtual image is formed 12cm from a concave mirror of focal length 18cm. calculate the position of the object and the magnification of the image(a) Explain with the aid of diagram how the image of an object is formed by a plane mirror(b) State four characteristics of the image (a) Define the following terms (i) principal focus (ii) radius of curvature (iii) principal focus(b) The screen of a pinhole camera is a square of side 160mm and it is 150mm behind the pole. The camera is placed 11m from a flag staff and positioned so that the image of the flag staff is formed centrally on the screen. The image occupies three-quarters of the screen. What is the length of the staff?WEEK ELEVENREFRACTION OF LIGHTRefraction of lightRefractive indexDetermination of Refractive indexTotal internal reflectionCritical angleRefraction of lightRefraction is the bending away of light from the normal as it passes from one medium to the other.There is a change in the direction and speed of a ray of light when it passes from medium to another medium of different density. This change in the direction of the light of the light ray which is due to difference in the speed of light in different media is called refraction.When a ray of light travels from optically less dense medium (air) to an optically dense medium (water, glass), it bends towards the normal.A ray passing from glass or water to air is bent away from the normal Incident ray normalMedium 1- air iMedium 2 - glass Refracted rayLAWS OF REFRACTION1. The incident ray, refracted ray and the normal at the point of incidence; all lie on the same plane.2. The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a given pair of media.The second law is known as Snell’s lawThe constant, n, is known as the refractive index of the second medium with respect to the first medium. It is a number which gives a measure of refraction or bending of light as it travels from one medium to another.As the ray of light travels from air to glass, the refractive index can be written as:From the principle of reversibility of lightFurthermore, Determination of Refractive indexEFFECTS OF REFRACTIONThe phenomenon of refraction is responsible for the following1 The bottom of a clear river or pond appears shallower than it really is2 A rod or spoon appears bent or broken when it is partially immersed in water or any liquid3 Letters in print seem to be nearer when we place a thick block of glass over themREFRACTION THROUGH RECTANGULAR PRISM The refractive index, n=sin(A/2+D/2)/sinA/2Total internal reflection & Critical angleWhen light passes at a small angle of incidence from a denser to a less dense medium e.g. from glass to air, there is a strong refracted ray. There is also a weak ray reflected back into the denser medium.When the angle of incidence increases, the angle of refraction also increases. At a certain increase of the angle of incidence, the angle of refraction is 900. This angle of incidence in the denser medium for which the angle of refraction in the less dense medium is 900, is referred to as the critical angle ( c). For angle of incidence greater than C, the refracted ray disappears and all the incident light is reflected back into the denser medium. At this point, the ray is said to experience total internal reflection. Example of total internal reflection is the mirage on the road, where the refractive density of warm air is less than that of cool air and light meets a layer at a critical angle, it suffers total internal reflection.REAL AND APPARENT DEPTHA thick slab of glass appears to be only two –third of its real thickness when viewed vertically from above. Similarly, water in a pond appears to be only three quarters of its real depth. Rays from a coin at the bottom of a bucket of water are refracted away when they leave water and enter the eyes. They appear as if coming from a virtual image, which is apparent depth while the actual depth of the bottom remains and is referred to as real depthRefractive index=real depth/apparent depthCLASSWORK 11State the laws of refractionThe velocities of light in air and glass are 3.0 x108 m/s and 1.8 x108 m/s respectively. Calculate the sine of the angle of incidence that will produce an angle of refraction of 300 for a ray of light incident on glassASSIGNMENT 11SECTION AThe direction of light ray changes as it passes from one medium to the other. The phenomenon is called (a) diffraction (b) reflection (c) dispersion (d) deviation (e) refractionThe horizontal floor of a reservoir appears to be 1.0m deep when viewed vertically from above. If the refractive index of water is 1.35, calculate the real depth of the reservoir (a) 2.35m (b) 1.35m (c) 1.00m (d) 0.50m (e) 0.35mWhich of the following is an application of refraction (a) eye glasses (b) car headlamp (c) touch light (d) shaving mirror (e) none of the aboveA ray of light is incident normally on an air-glass interface. What is its angle of refraction (a) 900 (b) 600 (c) 450 (d) 300 (e) 00A transparent block 5.0cm thick is placed on a dot. The dot when viewed is seen 3.0cm from the top of the block. Calculate the refractive index of the material of the block (a) (b) (c) (d) (e) SECTION B(a) What is: (i) refraction of a wave? (ii) Critical angle?(b) A water poured into a jar to a depth of 21cm. the bottom of the jar appears to be raised by 3cm when viewed vertically. Calculate the refractive index of the waterA ray of light incident at an angle of 300 at an air-glass interface (i) draw a ray diagram to show deviation of the ray in glass (ii) determine the angle of deviation
WEEK TWELVE: REVISION
WEEK THIRTEEN: EXAMINATION
SS3
SECOND TERM E-LEARNING NOTESUBJECT: PHYSICS CLASS: SS 3SCHEME OF WORKWEEK TOPICAlternating Current (I)Alternating Cur#ssqzhrent s6#(Is99*I)Models of the AtomRadioactivity (I)Radioactivity (2)Energy QuantizationPhoto-Electricity (x-ray) Conduction of Electricity in gases.Wave- Particle ParadoxRockets and Satellites; Component parts and functions Basic Electronics; Semiconductors.REFERENCE TEXTBOOKS AND PAST QUESTIONSNew School Physics by Prof. M.W Anyakoha.New System Physics by Dr. Chow.et.alWAEC past Questions packUTME past Question packMASTERS Physics Practical Manual.WEEK ONETOPIC: ALTERNATING CURRENT(I) CONTENTAlternating Current CircuitGraphical RepresentationPeak and R.M.S. ValuesA.C circuits are circuits through which an alternating current flows. Such circuits are used extensively in power transmission, radio and television, computer technology, telecommunication and in medicine. It varies sinusoid ally or periodically, in such a way as to reverse its direction pemriodically. The commonest form of such a.c can be represented by; I = Io sin 2π ft……………………………………………………………………… 1 = Io sin wtI is the instantaneous current at a time t, Io is the maximum ( or peak ) value of current or its amplitude; f is the frequency and w = ( 2π ft) us the angular velocity, (wt) is the phase angle of the current Also, V = Vo sin 2 π ft…………………………………………………………………………………..2 = Vo sin wtExamplesIf an a.c voltage is represented by 1f V = 4 sin 900 πt, calculate the peak and instantaneous voltage The peak voltage, Vo = 4v 2πft = 900πt f = 900 2 f = 450Hz w = 2πf = 900πPeak, and r.m.s. values of a.c EVALUATIONDifferentiate between peak and r.m.s voltage.Calculate the peak and instantaneous voltage of an a.c source represented by; V = 5 sin 500∏t.Variation of alternating current (or voltage) with timeAn alternating current ( or voltage) varies sinusoidally as shown in the diagram above. It is a sine waveform. The amplitude or peak value of the current Io is the maximum numerical value fo the current.The root mean square (r.m.s) value of the current is the effective value of the the current . it is that steady current which will develop the same quantity of heat in the same time in the same resistance.The r.m.s. value for the current is given by:Ir.m.s. = Io √2 ……………………………………………………. 3 The moving iron and hot wire meters measure the average value of the square of the current called the mean-square current. They are however calibrated in such a way as to indicate the r.m.s. current directly. This most a.c meters read the effective or r.m.s. values. The average value of an a.c voltage is zero.GENERAL EVALUATIONDifferentiate between heat and temperature.Mention five effect of heat.READING ASSIGNMENTNew School Physics p 447 -457WEEKEND ASSIGNMENTA 50Hz a.c circuit has a voltage of 220V and a current of 5.0A as its effective value. Determine the peak values of the voltage and its current. (a)311.0V and 1.71A (b) 331.0V and 7.10A (c) 311.00V and 7.10A(d)7.10V and 311.00ACalculate the peak voltage of a mains supply of r.m.s value of 220V. (a)112V (b) 150V (c) 222V (d) 311VIn an ac circuit the peak value of the potential difference is 180V. what is the instantaneous potential differences when the phase angle is 45o. (a)45V (b) 90V (c) 90√2 V (d)180VAn ammeter connected to an a.c circuit records 5.5A. What is the peak value of the current? (a) 7.8 (b) 7.1 (c) 3.9 (d) 3.When compared, the r.m.s value is .......... the peak value.(a) greater than(b) same(c) lower than (d) inversely proportional to.THEORYDistinguish between alternating current (a.c) and direct current (d.c). Explainthe term peak value and r.m.s. value as they apply to a.c circuitDraw a wave from diagram for an a.c and label the points at which the current is zero and maximum respectively. Determine the effective value of an a/c if its peak value is 15A.WEEK TWOTOPIC: ALTERNATING CURRENT (II)CONTENTA.C in Resistor, inductor and capacitorEnergy in inductance, Reactance and impedanceVector DiagramPower in A/CResonance and its applicationsAt any instant, the current through the resistor R, is I an the voltage across it is VFrom ohm’s law, V = IRThus the current is given by I = V R.But V = Vo sin wt I = V = Vo sin wt R R I = Io sin wtThe voltmeter and ammeter connected in the circuit will read the r.m.s values of voltage and current I r.m.s. = Vr.m.s R. …………………………………………………………………..4The voltage and the current are said to be in phase or in step with each other . This means that both of them attain their maximum, zero and minimum values at the same instant in time.Capacitance in an a.c circuitIn the circuit above, an a.c. voltage is connected in series with a capacitor. IC π/2 rad VCIc leads Vc by π radians or 90o or by ¼ cycle 2The voltage (v) and current ( I ) are out of place ( not in step) . the current is said to lead on the voltage and the voltage is said to lad on the current. The phase difference between the current and the voltage is 90o or ( π/2) radianV = Vosinwt I = Io sin (wt + π/2)The capacitor opposes the flow of current. This opposition to the flow of a.c. offered by the capacitor is known as capacitive reactance, Xc. This is given by the relation Xc = 1 2πfC ………………………………………………..5when an a.c.. voltage of frequency f is applied to a capacitance, c, then V = IXc …………………………………………………………………………… 6In other words, from ohm’s law relation, when applied to a capacitor.In it, R is replaced by: Xc = 1 . Hence the unit of Xc is in ohms 2πfCExampleA 2µF capacitor is connected directly across a 150Vrms, 60Hz a.c source. Find a) the r.m.s value of the currentb) the peak value of current. Xc = 1 . 2πfC = 1 2π x 60 x ( 2 x 10-6)Ώ = 1324.4 ΏFrom V = IXc I r.m.s. = Vrms = 150 . Xc 1324.4 = 0.113A.Peak current, Io = √2 Ir.m.s. = 0.160AEVALUATION Determine the r.m.s. value of the current in an a.c circuit with a 5.5µF capacitor across a 220Vr.m.s, 50Hz.Inductance in A.C CircuitVL leads IL by π/2 radians or 90o. The induced e.m.f. in the inductor L opposes the change in the current.As a result the current is delayed behing the voltage in the circuit. The current lads behind V by π/2 radian or 90o or by ¼ cycle. I and V have a phase difference of 90o (π/2) π/2 rad VL IL V = Vo sin wt I = Io sin (wt – π/2 ). Like R and C, an inductor L opposed the flow of current; i.e it has an impedance effect known as inductive reactance, XL. V = I X L …………………………………………………………………………………… 7The unit of XL is in ohms XL = 2πfL ………………………………………………….. 8The unit of L is Henry (H), f is in hertz (Hz) and XL is in ohms.Reactance is the opposition to the flow of a.c offered by a capacitor or an inductor or both.Find the impedance across an inductor of 0.2H inductance when an a.c voltage of 60Hz is applied across it, if the voltage is given by V = 150 sin 120πt. Calculate the r.m.s and peak values of the current. XL = 2 πfL = 2π x 60 XL = 120πL = 120 x π x 0.2 = 75.40Ώ V= 150 sin 120 π tVo = 150V F = 60HzVrms = 0.76 = 0.7 x 150 = 105VIrms = Vrms = 105 XL 75.4= 1.39AIo = Vo = 150 XL 75.4 = 1.99AEVALUATION Determine the r.m.s. value of the current in an a.c circuit with a 5H capacitor across a 220Vr.m.s, 50Hz.Series Circuit Containing Resistance (R)Inductance (L) and Capacitance (C)If an alternating voltage V = Vo sing 2πft is put across the circuit, it is observed that a steady state current given by I = Iosin2πft will flow along the circuit . The maximum or peak value of the current is given by Io = Vo √ (R2 + (XL – Xc)2 ) …………………………………………………………………….. 9 = Vo √R2 + X2 X= XL -XC.Let Z =√ ( R2 + (XL –XC )2 ) :. Io = Vo ZIr.m.s. = Vr.m.s ZZ is known as the impedance of the circuit.Impedance (Z) is the overall opposition of a mixed circuit containing a resistor, an inductor and or a capacitor. It is measured in ohms. Xc = 1 WC = 1 2πfC XL = WL = 2πfL = Z = √R2 + ( wL – 1 )2 ) wc Z = √R2 + ( 2πfL - 1 )2 2πfCin summary V= IR VL = I X L Vc = I X C V = IZ V= I √(R2 + (XL – Xc)2 )………………………………………………………………… 10Example(1) Find the r.m.s. value of an alternating current whose peak value is 5A. Irms = Io √2 = 0.707Io = 0.707 X 5 = 3.53A.(2) in a.c circuit the peak value of the potential difference is 180v. What is the instantaneous p.d when it has reached 1/8th of a cycle/1 cycle = 360o 1/8 of a cycle = 360/8 = 45oE = Eo sin wt = Eo sin 45 = 180sin 45 = 180/√2 = 90√2V.3. A circuit consist of a resistor 500 ohms and a capacitor 5uF connected in series . if an alternating voltage of 10v and frequency 50Hz is applied across the series circuit. Calculate:i. the reactance of the capacitorii. the current flowing in the circuitiii. the voltage across the capacitor (b) If the capacitor is replaced with an inductor of 150mH, calculate the impedance and voltage across the inductor. Xc = 1 2πfc = 1 2π x 50 x 5 x 10-6 = 636.62 ohmsII. Z = √R2 + Xc2 = √5002 + 636.622 = 809.5 Ω I = V = 10 . Z 809.5 = 12.35 x 10-3 A 12.35 mA.iii. Vc =I X c = 12.35 x 10-3 x 636.62 = 7.86 V(b)XL = WL = 2π x 50 x 150 x 10-3 = 47.12 ΩZ = √ R2 +XL 2 = √5002 - (47.12)2 = 497.7 ΩI = 10 . 497.7 = 0.02AVL = 1 x L = 0.02 x 47.12 = 942.4mA.EVALUATION An a.c circuit consist of a resistor 100Ω, an inductor 20H and a capacitor 5.0µF connected in series. If the source has 220Vr.m.s, 50Hz across it, calculate; (i). the impedance, (ii). the current flowing in the circuit.VECTOR DIAGRAMWhen an alternating voltage is placed across a R.L.C series circuit, the resulting alternating current I. has the same frequency as the voltage (v0 but the two differing phase or are said to be out of phase.Phase is the state of vibration of a periodically varying sytems at a particular time, wt = phase angleTwo vibrating systems with the same frequency are said to be inphase if their maximum, minimum and zero values occur at the same time; otherwise they re said to be out of phase.The phase difference between the voltage and the current through an RLC series circuit is given by Tan θ = X R X = reactance =XL – Xc and R is the resistance .For a circuit containing only a resistance R, the a.c voltage vibrates in phase or in step with the alternating current.Thus Ǿ = OFor a circuit containing only a capacitance C, Vc and Ic are out phase by 90⁰ or (π/2) radian. This means that the angle by which a particular phase Ic is in advance of a similar phase of Vc is 90⁰ or π/2 radian or ¼ cycle If Vc = Vo sin wtThen Ic = Io sin (wt - π/2).iii. If only an inductor L is connected to the a.c voltage, the current IL, lags on the voltage vL by π2 radians VL = Vo sin wt IL = Io sin (wt – π/2)In a circuit containing RLC the current is the same for all the components of the circuit, and is in phase with the voltage across R. let VR be the reference vector, the other voltage vectors acts as shown VL- VC VL XL- XC XL VR R VR R VC XCThe effective voltage V is given by V2 = V2R + (VL – VC)2 …………………………………………………………………….. 11 Tan Ǿ = VL – VC VR = XL - XC R.If XL > XC, Ǿ is positive and I lags.If XL < Xc,Ǿ is negative and I leads VFor R and L series, we have V2 = V2R + V2L.I = V . √R2 + X2LZ = √R2 + X2LCurrent I, lags on the applied voltage by Ǿ given by Tan Ǿ = VL VR = XL R V II lags V or V leads IFor R and C in series V2 = V2R + V2CI = V √R2 + X c2Z = √R2 + Xc2Tan Ǿ = Vc = Xc VR RV lags I or I leads V.POWER IN AN A.C CIRCUITThe average power in an a.c circuit is given by; P = IV cos ǾI, V are the effective (r.m.s) values of the current and voltage respectively and Ǿ is the angle of lag or lead between them . The quantity cos Ǿ is known as the power factor of the device. The power factor can have any value between zero and unity for Ǿ varying from 90o to 0o. For Ǿ = 90o or cos Ǿ = 0, average power P is zero. A power factor of zero means the device is either a pure reactance, inductance or capacitance. Thus no power is dissipated in an inductance or capacitance.However, if I is the r.m.s value of the current in a circuit containing a resistance R, the power absorbed in the reactance is given by P = I2R …………………………………………………………… 12For an a.c circuit, the instantaneous power is given by P =IV (instantaneous value)Power factor Cos Ǿ = Resistance Impedance …………………………………………………………. 13ExampleA series circuit consist of a resistance 600 ohms and an inductance 5 henry’s .An a.c voltage of 15v(rms) and frequency 50hz is applied across the circuit, calculatei the current flowing through the circuitii. the voltage across the inductoriii. the phase angle between I and the applied voltageiv. the average power suppliedv. the p.d across the resistance.XL = 2πfl = 2 πx 50 x 5 = 500πohmsZ = √R=Xl = √(600)2 + (500π) = 1.69 X 10 3 ΩIr.m.s = Vrms = 15 = 8.88 x 10-3 A = 8.88mA Z 1.69 x 103 ii. voltage across the inductor VL = I XL = 8.88 x 10-3 x 500 π = 4.44πvolts = 14.95 voltsiii. tan Ǿ = XL = 500π = 2.62. R 600Ǿ = tan-1 ( 2.62) = 69.10iv. Power supplied P = I2R = (8.88 x 10-3)2 x600 = 4.73 x 10-2 wv.p,d across R. V =IR = 8.88 x 10-3 x 600 = 5.53ohms.EVALUATION An a.c circuit consist of a resistor 100Ω, an inductor 20H and a capacitor 5.0µF connected in series. If the source has 220Vr.m.s, 50Hz across it, calculate the; (i) voltage across the inductor, (ii) voltage across the capacitor.In the circuit in (1) above, determine the; (a)average power in the circuit, (b) power developed in (i)the inductor, and (ii)the capacitor. RESONANCE IN RLCSeries CircuitThe current in RLC series circuit is given by: I = V = V . Z √R2 + (XL – Xc )2The maximum current is obtained in the circuit when the impedance is minimum. This happens when XL = Xc 2πfL = 1 . 2πfCResonance is said to occur in an a.c series circuit when the maximum current is obtained from such a circuit. The frequency at which this resonance occur is called the resonance frequency (fo). this is the frequency at which XL = Xc 2πfoL = 1 . 2πfoC 4π2fo2LC = 1 fo2 = 1 . 4π2LC fo = 1 2π √LC …………………………………………………………… 14since w = 2πfwo = 1 . √LCNOTE: At f = fo, the current is maximum.APPLICATION OF RESONANCEIt is used to tune radios and tvs. Its great advantage is hat it responds strongly to one particular frequency.ExamplesAn a.c voltage of amplitude 2.0 volts is connected to an RlC series circuit. If the resistance in the circuit is 5 ohms, and the inductance and capacitance are 3mh and 0.05 uf respectively. Calculate:the resonance frequency,fothe maximum a.c. current at resonance.Fo = 1 . 2π√LC = 1 . 2π√3 x 10-3 x 0.05 x 10-6 = 1 . 2π√3 x 10-11 = 1299. 545Hz 1.3KHzAt resonance X = R since XL =XC I = Vo R = 2 5 = 0.4AREADING ASSIGNMENTNew School physics pag 458-463GENERAL EVALUATIONWhy is water not used as a thermometric substance.Differentiate between evaporation and boiling.WEEKEND ASSIGNMENT A voltage supply of 12V r.m.s anf frequency of 90Hz is connected to a 4Ω resistor. Calculate the peak value of the current . (a) 48.8A (b) 30.0A (c) 27.5A (d)4.2AA 2µF capacitor is in series with a resistor of 5000Ω. A voltage of 5V r.m.s and frequency, I= 100Hzis connected to them. What is the capacitive reactance?795.5Ω (b) 895.5 Ω (c)1795Ω (d) 2005.0Ω3. At what frequency will 20uf capacitor have a reactance of 500 ohms? (a) 100Hz (b) 50Hz (c) 150Hz (d) 100π Hz (e) 30Hz π π π π π4. In an RLC series a,c circuit power is dissipated in (a) Resistance only (b) Reactance only (c) Resistance and reactance (d) Resistance, inductance and capacitance5. In a series L-C circuit, the inductance and the capacitance are 0.5H and 20µF respectively. Calculate the resonance frequency of the circuit (a) 24.2Hz (b) 36.7Hz (c) 50.3Hz (d) 60.5HzTHEORYExplain what is meant by the terms impedance, phase angle and reactance as applied to an a.c. circuit. Calculate the impedance and phase angle for an a.c. circuit having a 100ohms resistance, 5uf capacitor in series if an a.c voltage of frequency 100Hz is applied across the circuit.Draw a vector diagram of the relationship of I and V for an a.c. circuit containing (a) a pure inductor (b) a pure capacitor (c ) a pure resistorWEEK THREEMODELS OF ATOMSCONTENTThompson, Rutherford, Bohr Models and LimitationsAssumption of Bohr theoryElectron Cloud ModelStructure of Nucleus, Protons, IsotopesTHOMPSON MODELThompson proposed an atomic model which visualized the atom as a homogenous sphere of positive charge inside of which are embedded negatively charged electrons. Sphere of positively charged matter Embedded electronHe also determined the ratio of the charged to mass, e/m , of electrons, and found e/m to be identical for all cathode rays particles, irrespective of the kind of gas in the tube or the metal the electrons are made of.RUTHERFORD MODELHe proposed a planetary model of the atom which suggested that the atom consists of positively charged heave core called the nucleus where most of the mass of the atom was concentrated .around this nucleus, negatively charged electrons circle in orbits much as planets move around the sun. Each nucleus must be surrounded by a number of electrons necessary to produce an electrically neutral atomLIMITATION OF RUTHERFORD MODELIt predicts that light of a continuous range of frequencies will be emitted whereas experiment show line spectra instead of continuous spectra.It predict that atoms are unstable-electrons quickly spiral into the nucleus- but we know that atoms in general are stable, since the matter around us is stable.Clearly Rutherford’s model was not sufficient to explain experimental observations. Some sot of modification was needed and this was provided by Neils Bohr.EVALUATION What are the limitations of Rutherford’s model?THE BOHR’S MODELHe suggested a model of hydrogen atom in whichthe electron moves around the nucleus in certain specific circular orbits called energy level and that the centrifugal force due to this motion counter balances the electrostatic attraction between the electron and the nucleus. The electrons can move without losing or radiating energy in such orbits. He called the possible orbits stationary states. Only orbits of particular radii were possible. In general, the higher the energy of the electron, the farther its orbits from the nucleus.ii. the energy of an electron in an atom cannot vary continuously to a limited number of discrete or individual values. The energy of the electron is said to be quantized ( i.e can have only discrete values). He thus postulated that electrons in an atom cannot lose energy continuously but mist do so in quantum ‘jumps’. He postulated that light is emitted only when an electron jumps from one stationary state to another of lower energy. When such a jump occurs, a single photon of light would be emitted whose energy is given by hf = Eu – ElEu = Energy of upper stateEl = energy of lower stateh = planck constant ( h = 6.67 x 10-34 Js)f = frequency of emitted lightBohr was able to account for the appearance of line spectrum rather than continuous spectrum.An electron absorbs energy when it transfers to higher energy level ( excitation) Photon An electron emits a photon when it moves to a lower energy level.iii. The third postulate of Bohr’s model was that angular momentum values of the electron in an atom are quantized, that is, they are restricted to a limited number of discrete values that are integral 9n0 multiples of a constant, planck’s constant (h) divided by 2 π. That angular momentum L =n (h) 2π n = 1,2,3,4…The integral n is called a quantum numberBohr model is also known as the Bohr – Rutherford model since it was an extension of Rutherford planetary model. The great success of Bohr theory is that;it gives a model for why atoms emits, line spectra and accurately predicts, for hydrogen, the wave lengths of emitted lights or the frequencies of the lines in the hydrogen spectrum.It offers an explanation for absorption spectra; photons of just the right wavelength can knock an electron from one energy level to a higher one. To conserve energy, the photon must have just the right energy. This explains why a continuous spectrum passing through a gas will have dark (absorption) lines at the same frequencies as the emission line.It ensures the stability of atoms by stating that the ground state is the lowest state for an electron and there is no lower energy level to which it can go and emit more energy.It accurately predicts the ionization energy of 13.6ev for hydrogen.EVALUATIONWhat are the successes of Bohr’s model?THE ELECTRON CLOUD MODELThis model visualizes the atom as consisting of a tiny nucleus of radius of the order of 10-10 - 10-15m. The electron is visualized as being in rapid motion within a relatively large region around the nucleus, but spending most of its time in certain high probability regions. Thus, the electron is not considered as a ball revolving around the nucleus but as a particle or wave with a specified energy having only a certain probability of being in a given region in the space outside the nucleus. The electron is visualized as spread out around the nucleus in a sort of electron – cloud.Chemists prefer to consider the electron in terms of a cloud of negative charges (electron cloud), with a cloud being dense in regions of high electron probability and more diffuse in region of low probability. The probability of finding the electron inside the spherical boundary is high. The probability then decreases rapidly as the distance of the thin shell from the nucleus increases.ATOMIC STRUCTURE AND CHEMICAL BEHAVIOUR Today we consider the atom as made up of tiny but massive nucleus at the centre and outside the nucleus is a cloud of electrons which move in wave-like orbits or shells around the massive nucleus. The nucleus consists of protons which carry positive changes and neutrons which carry no charge. The neutron and proton together constitute the nucleon. All the mass of an atom is concentrated in the central nucleus. The protons, neutrons and electrons are the fundamental sub atomic particles of the atom.The electron is the lightest particle of an atom, with a mass (Me) of 9.10-31kg and an electronic charge e- = 1.6 x 10-19 C.The proton has a mass of 1.67 x 10-27kg which is over 1836 times heavier than the mass of an electron. It carries a positive charge, e+ = 1.67 x 10-29 c ( i.e e+ = e- = 1.6 x 10 -10). There are the same number of protons in the atoms of different elements.in a neutral atom, the number of protons equals the number of electrons.We denote the atom of an element X by AzX A = mass number Z = atomic numberThe atomic number or proton number (Z) is the number of protons in the nucleus of an element. The mass number or nucleon number (A) is the total number of protons and neutrons in an atom of an element ISOTOPESIsotopes are atoms of the same element which have the same atomic number (X) but different mass number. Isotopes are thus atoms with the same number of protons, but different number of neutrons. Isotopes have similar chemical properties because they have the same number of electrons round the nucleus. Chemical combinations is due to an exchange of outer or valence electrons between elements.Examples of isotopesi. 35 17Cl (17 protons , 17 electrons, 18 neutrons)3717Cl (17 protons, 17 electrons, 20 neutrons)b) 126Cl (6 protons, 6 electrons, 6 neutrons)136Cl (6 protons, 6 electrons, 7 neutrons)c) 168O (8 protons, 8 electron 8 neutrons)178O (8 protons, 8 electrons, 9 neutrons)188O (8 protons, 8 electrons, 10 neutrons)23892U (92 protons, 92 electrons, 146 neutrons)238\592U (92 protons,92 electrons, 143 neutrons)23492U (92 protons, 92 electrons, 142 neutrons)GENERAL EVALUATIONMention four effect of thermal expansion of solidMention four the advantages and disadvantages of thermal expansion of solidREADING ASSIGNMENTNew School Physics pgs 464-471WEEKEND ASSIGNMENT 1. Which of the following statement is not true of the isotope of an element? They A. Are atoms of the same element B. Have the same chemical properties C. Have the same atomic mass D. Have the same mass number2. Which of the following representation is correct from an atom X with 28 electrons and 30 neutrons? A. 3028X B 2830X C 5830X D. 5828X E. 302X3. Bohr theory provides evidence for the A structure of the atom B. positive charge of an electron C existence of energy level in the atom D. positive charge on a proton 4. Which of the following particles determine the mass of an atom? A. protons and neutrons B. Neutrons only C. protons and electrons D. Neutrons and electrons E. Protons only 5. Which of the following names is not associated with the models of the atom. A. Isaac Newton B. Neils Bohr C. J.J. Thompson D. Ernest Rutherford E. John Dalton THEORYDescribe the essential feature of the Bohr- Rutherford Model of the atom. What are its successes and its failures. How does it account for line spectra.What are the essential features of the Electron –Cloud Model of the atom. Illustrate with a diagram.WEEK FOURTOPIC: RADIOACTIVITY (1)CONTENTSEmission of Alpha and Beta particles and Gamma raysProperties and peaceful uses of radioactivityRadioactive hazards and safety precautionsBinding energyRadioactivity is the spontaneous decay or disintegration of the nucleus of the atom of an element during which it emits α, β or γ rays or a combination of any or all the three and energy ( or heat).If a small sample of radium is placed at the bottom of a small hole drilled in a block of lead. The radiation emitted from this radium emerged from the hole in a narrow beam. if the rays were subjected to a strong magnetic field placed at the side of a beam. A photographic plate situated at appropriate sides to receive the rays showed that the paths of some rays were bent to the right, some to the left and some went straight on, unbent.Electrically charged plates placed at the side of the beam gave the same effect. The radiations that was bent towards the negative electric plate or the south pole of the magnetic field are called the Alpha particles ( α –particles ) The radiations deflected towards the positive electric plate or the North pole of the magnetic field is called Beta particles (β – particles ). The radiation that was neither affected by the electric or magnetic field is called gamma rays (γ ). They are actually electromagnetic radiations.Radioactive Decay; Half-life, Decay ConstantRadioactivity is a spontaneous process. It goes on independent of external control, it is not affected by temperature, or pressure or by chemical treatment. It is a random process as no one can predict which atom will disintegrate at a given time.The half-life of a radioactive element is the time taken for half of the atoms initially present in the element to decay. The rate of decay of radioactive elements is found to be proportional to the number of atoms of the material present. If there are N atoms of a radioactive element present at a time, ti, then the probable number of disintegration per unit time or activity. N α - dN DtThe minus sign arises from the fact that N is decreasing with time dN = -λN dtλ is a constant of proportionality called the decay constant. :. λ = - 1 dN N dtHence, decay constant is defined as the instantaneous rate of decay per unit atom of a substance Λ = No of atoms disintegrating per second Np pf atoms in the source at that timeBy integration N =Noe-λtNo = Number of atoms present at time t = oN = Number of atoms present at time t T = 0.693 ΛExampleA certain radioactive element has a half-life of 10years.How long will take to lose 7/8 of its atoms originally present.How long will it take until only ¼ of the atoms originally present remain unchanged.If 7/8 of its atoms has been lost, 1/8 remains Half-life = 10years N/4 remains after 20 yearsN/8 remains after 30 years:. it takes 30 years to lose 7/8 of its atomsN/2 remain unchanged after 10 yearsN/4 remains unchanged after 20 yearsAns = 20yearsEVALUATION If the half life of a radioactive substance is 2.45 X 108s, determine is decay constant. TRANSFORMATION OF ELEMENTSThere are two types of radioactivityNatural radioactivity Artificial radioactivityNatural radioactivity is the spontaneous disintegration of the nucleus of an atom during which α particles,β particles or γ rays and heat ( or energy) are released. When a radioactive elements undergoes radioactive decay, it may emit either α ,B, or γ rays. This changes the atomic number of the element, hence a new element is formed. 226 88X α 42He + 22286Rn + energy 22288 2B 2 0-1e + 22290Ra + energy238 U 2α, 2β 2 ( 42He) + 2 -1oe + 230 Th + energy 92 91234 U β 90 0-1e + 23491Pa + energyGenerally we represent alpha (α) decay byA 42 He + A - 4 y + energy Z Z - 2And B decay byA Z 0-1 e + A y (z+1)ARTIFICIAL RADIOACTIVITYIf the radioactivity is induced in an element by irradiation with for neutrons, the process is known as artificial radioactivity. By irradiation, it means exposure to radiation either by accident or by intent.4 2He + 14 7N 18 9F 17 8O + 1 1H + energyin artificial radioactivity, an ordinary materials is made radioactive by bombarding itwith radioactive particles.4He + 27 Al 30P + 1n 10 n + 63Li 31H + 42He + energy10 n + 2412Mg 2411Na + 11P + energy42He + 94Be 126C + 10n + energy10n +5927Co 6027Co + energyIsotopes can also be made artificially by bombarding neutrons, or protons or deuterons at elements e.g.3410S + 10n 3510S + energy7910Br + 10n 3510Br + energysuch artificially produced isotope are unstable and decay with the emission of α – particles, β –particles and γ – rays. They are called radio isotopes.GENERAL EVALUATIONWith the aid of a diagram, explain the anomalous behaviour of waterDescribe an experiment to determine the apparent cubic expansivity of a liquidREADING ASSIGNMENTNew School Physics pg 468-471WEEKEND ASSIGNMENT1. The phenomemon of radioactivity was first discovered by (A) Marie Curie (B) J.J. Thompson (C) Henri Becquerel (D) Nent Bohr (E) Enrico Fermi2. A radioactive substance has a half-life of 3 days. If a mass of 1.55g of this substance is left after decaying for 15days,dertermine the original value of the mass (A) 49.6g (B) 37.2g (C) 24.8g (D) 12.4g3. Which of the following is usually used to cause fission in an atomic reactor? (A) alpha particles (B) beta particles (C ) electrons (D) neutrons4. A substance has a half-life 30 mins after 6mins the count rate was observed to be 400. What was its count rate at zero time. (A) 200 (B) 1200 (C) 1600 (D) 24005. A nuclide 20284Y emits in succession an α-particle and β-particle. The atomic number of the resulting nuclide is (A) 198 (B) 83 (C ) 82 (D) 80.THEORY1 (a) Define radioactivity; half-life and decay constant.(b) Write down the relation between half-life and decay constant (c) In 180 minutes, the activity of a certain radioactive substance falls to one –eight of its original value. Calculate its half-life.2 (a)A nuclide X emits β-particle to form a daughter nuclide Y. write a nuclear equation to illustrate the charge conservation.(b) the isotope of a nuclide has a half-life of 5.4X103s.Calculate its decay constant.WEEK FIVETOPIC: RADIOACTIVITY (2)CONTENTSArtificial TransformationNuclear FissionNuclear FusionNuclear EnergyChain reactionPeaceful uses of nuclear energy.ARTIFICIAL TRANSFORMATION Artificial transformation is induced in an element by irradiation (exposure to radiation) either by accident or by intent) . It was first achieved by Rutherford. An ordinary material not normally radioactive is made radioactive by bombarding it with radioactive particles e.g 42He + 27 13Al 3015 P + 10n NUCLEAR ENERGYThe protons and neutrons (nucleons) in the nucleus of each atom are held together by very powerful nuclear forces. An enormous amount of energy is required to tear the nucleon apart. Enrico Fermi (1934) discovered that the nucleus can be split by bombarding it with a slow neutron. 10n + 23592U 14156Ba + 92 36Kr + 3 10n + energy.He discovered that the total mass of the component products is less than the mass of the original materials. The difference in mass (mass defect) is a measured of the nuclear energy released.According to Albert Einstein E = ∆ mc2 E = nuclear energy ∆m = mass defect c= velocity of light ( 3.0 x 108ms-1)NUCLEAR FISSIONThis is the splitting up of the nucleus of a heavy element into two approximate equal parts with the release of a huge amount of energy and neutrons.Fission occurs with most of the massive nuclei. When the heavy nucleus is bombarded by slow neutron, several neutrons are produced as by –products.These neutrons may cause the splitting of other nuclei, which in turn yield more neutrons which may further split other nuclei and so on.Thus a chain reaction is set in motionA chain reaction is a multiplying and self maintaining reaction . When the size of the nuclei exceeds a certain critical mass, there is a rapid production of neutron accompanied by a release of tremendous amount of energy in a nuclear explosion. This is the principle of the atomic and nuclear fission bombs. It is also the process used in the present day nuclear power station .NUCLEAR FUSIONThis is a nuclear process in which two or more light nuclei combine or fuse to form a heavier nucleus with the release of a large amount of energy e.g.21H + 31H 41 He + 10n + energyTo bring the two lights nuclei together in a fusion process, very high temperature of the order 10,6000C are required to overcome the coulomb repulsive forces between the two nuclei.ADVANTAGES OF FUSION OVER FISSION Fusion is more easily achieved with lightest element e,g hydrogen.The raw materials required from fusion are more readily and cheaply available Fusion process produces less dangerous by-products.Peaceful uses of nuclear energyMany nuclear power plants are now being used to generate electricitySeveral fission products obtained in nuclear reaction are used for radiotherapy.Radio isotopes from nuclear plants are used in agriculture as tracers and preservatives.some space crafts. Ships and submarines are powered by nuclear energy.GENERAL EVALUATIONDefine the following terms (a) Conduction (b) Convection (c) RadiationWith the aid of a diagram, explain how the construction of a thermos flask minimizes heat exchange with the surrounding.WEEKEND ASSIGNMENT 1. If a nucleus 31H decays, a nucleus of 32H is formed accompanied with the emission of (a) beta particles (b) gamma particle (c) alpha particle (d) x-rays.2. The count rate of radioactive substances diminishes from 600 to 150 in 60 secs. Determine the half life of the substance (a) 15 secs (b) 30 secs (c) 45 secs (d) 60secs.3. a radioactive substance half life of 20hrs. what fraction of the original radioactive nuclide will remain after 80hrs (a) 1/32 (b) 1/16 (c ) 1/8 (d) 15/164. a material of mass 1.0X10-3kg undergoes fission process which decreases its mass by 0.02%. calculate the amount energy released in the process [c=3X108m/s] (A) 1.8X1020J (B) 1.8X1013J (C) 1.8X1011J (D) 1.8X1010J 5. In a nuclear reaction the mass defect is 2.0X10-6g. Calculate the energy released, given velocity of light is 3X108m/s. (A) 9.0X1007J (B) 1.8X1008J (C) 1.8X1009J (D) 9.0X1010JTHEORY1. Explain the terms nuclear fission and nuclear fusion 2. Nuclear reaction is given by the equation 2 1H + 31H 42H + 10n + energy(a) What type of nuclear reaction is it?(b) state two component in a nuclear reactor used to control chain reactionWEEK SIXTOPIC: ENERGY QUANTIZATIONCONTENTEnergy QuantaEnergy Level in AtomsKinetic Energy of Emitted PhotonBohr suggested that the electron in the atom exist in discrete energy known as quantization which can be removed from one level to the other. Energy in such bodies is emitted in separate or discrete energy packet called energy quanta E =hf h = Planck’s constant. f = frequencyENERGY LEVEL IN AN ATOMElectrons in atoms are arranged around their nuclei in position known as energy level or electron shell. It requires more energy to remove electrons from the first energy level than to remove electrons from any of the other higher levels. The energy of an electron is given by the relation . E = - 1 R n2n = electron quantum numberR = a constantThe minus sign signifies that work must be done on the electron to remove it from the atom.ENERGY LEVEL DIAGRAM E5 n =5 E4 n=4 E3 n=3 E 2 n =2 E 1 n =1 E o n = 0 (ground state)The ground state is the stable state or an atom corresponding to its minimum energy. When an atom is heated with an energetic particle, the atom is excited. An excited state is an allowed state of higher energy when the atom is unstable. One electron volt (IeV) is the energy acquired by an electron in falling freely through a p.d of 1 Volt = 1.6 x 10 -19J.During the excitation from lower energy level, the potential energy is converted into Kinetic energy so that the electrons eventually acquire a velocity given by: K. E = ½ MV2 = eV.The energy gained by electron = charge x p.d = eV. Therefore, the electron moves from one level to the other according to the relation. En – Eo = hf = eV λWorked example1. The change in energy level of an electron in an atom is 6.2 x 10 -21J. Calculate : (a) the frequency of the photon (b) the wavelength (C = 3.0 x 108 ms -1, h = 6.625 x 10 -34Js) ∆ E = En-Eo = 6.2 x 10 -21J ∆E = hff = ∆E = 6.2 x 10-21 h 6.625 x 10-34f = 9.358 x 10 2HzBut C = f λ:. λ = C = 3.0 x 108 f 9.4 x 10122. An atom excited to an energy level E2 = -12 .42 x 10-19J falls to a ground level of energy Eo = - 30.3 x 10-19J. Calculate the frequency and the wavelength of the emitted photon.∆E = E2- Eo = -12.42 x 10-19 – ( -30.3 x 10-19J ) = 17.88 x 10-19Jf = ∆E = 1.788 x 10-18 h 6.625 x 10-34f = 2.698 x 1015 Hz.3. The ground state of hydrogen is -26.3eV and the second state is -10.3eV. Calculate the wavelength of the radiation if the electron returns to the ground state.∆E = E2 – EO = -10.3EV – (-26.3ev) = 16ev 1ev = 1.6 x 10-19 J:. 16ev = 16 x 1.6 x 10-19J∆E = hf = hc λ:.λ = hc = 6.625 x1034 x 3.0 x 108 ∆E 16 x 1.6 x 10-19 = 1.9875 x 10-25 25.6 x 10-18λ = 7.76 x 10-19 m4. If the p.d by which an electron moves is 1.5kv. Calculate the velocity with which the electron moves if the ration of its charge to mass is 1.9 x 1011 c kg-1 (b) the kinetic energy . KE = ½ mv2 = ev 2ev =mv2 v2 = 2ev m But e/m = 1.8 x 1011 V = √2 x 1.5 x 103 x 1.8 x 1011 V = 2.3 x 107m/s Ke = eV = 1.6 x 10-19 x 1.5x 103 = 2.4 x 10-16 J.GENERAL EVALUATIONWith the aid of a diagram, explain charge distributionName two devices that can store charge.READING ASSIGNMENTNew School physics pgsWEEKEND ASSIGNMENT 1. When an atom is in ground state, it is said to be (A) excited (B) stable (C) ionized2. In which of the following transitions is the largest quantum of energy liberated by an hydrogen atom, when the electron changes energy level? (A) n=2 to n=1 (B) n=2 to n=3 (C) n=3 to n=2 (D) n=1 to n=23. Which of the following give rise to the line spectra obtained from atoms. (A) change of electron from a higher to lower energy level (B) potential energy of the electron inside an atom (C ) Excitement of an electron in the atom4. A 50KV is applied across an x-ray tube. Calculate the maximum velocity of the electrons produced. [Me= 9.11X10-31Kg, e= 1.6X10-19C] (A) 4.2X108m/s (B) 1.8X108m/s (C) 4.2X105m/s (D) 1.8X105m/s5. The nucleon number and the proton number of a neutral atom are 238 and 92 respectively. What is the number of neutrons in the atom? (A) 146 (B) 330 (C) 73 (D) 52.THEORY1. An electron of charge 1.6X10-19C is accelerated in a vacuum from rest at zero volt towards a plate 40KV. Calculate the kinetic energy of the electron2. An electron jumps from one energy level to another in an atom radiating 9.0x10-19J. If h = 6.6 x 10 -34Js and C = 3.0 x 108m/s, what is the wavelength, and the frequency of the radiation. WEEK SEVENTOPIC: PHOTO ELECTRIC EFFECTCONTENTApplicationPhotoelectric EquationThreshold frequencyWork funtionx-rayWhen light falls on a metal surface, electrons are emitted, this process is called photo electric effect emission, the emitted electrons are known as photo electrons.The maximum kinetic energy of the photo electrons are independent of the intensity of the incident light but depends on the frequency or wavelength of the incident light.Increasing the intensity of light increases the number of photo electron but does not increase the energy or velocity. The absorbed energy is used to overcome the potential barrier of the photo electrons.APPLICATIONPhotoelectric emissions is used in the following : I Burglary alarmii Television cameraiii Automatic devices for switching light at dusk e. street light.iv. Sound production of film trackv. industrial controls and counting operations.EINSTEN PHOTOELECTRIC EQUATIONEinstein photoelectric equation is given by E = hf – w W = hfo E = maximum kinetic energy that can be given to a photo electrons W = work function fo = Threshold frequency hf = W = maximum energy of the liberated. Photoelectrons.THRESHOLD FREQUENCY (fo)This is the lowest frequency that can cause photo emission of electrons from a metallic surface. Below threshold frequency, emission will not occur.WORK FUNCTION (W = hfo)This is the minimum energy required to liberate electrons from a metallic surface.W = hfo.ExampleCompute the frequency of the photon whose energy is required to eject a surface electron with a kinetic energy of 3.5 x 10-16 eV if the work function of the metal is 3.0 x 10-16 eV (h = 6.6 x 10-34JS, 1eV = 1.6 x 10-19J ). E = hf – w E + w = hf E + W = f H = ( 3.5 + 3.0) x 10-16 x 1.6 X 10-19x 10-34 = 6.5 x 1.6 x 10-16 -19+ 34 6.6 = 1.58 x 10-1 HzTHRESHOLD WAVELENGTHThe threshold wavelength is the longest wavelength that will produce photo electrons when the surface is illuminated. W = hfo W = hc λo λo =hc WThe work frequency of Lithium is 2.30eV, calculate the maximum energy in Joules of photoelectrons liberated by light of wavelength 3.3 x 10-17mthe threshold wavelength of the metal.W = 2.3 ev E = hf – w = hc - w λ = 6.6 x 10-34 x 3.0 x 108 – (2.3 x 1.6 x 10-19) 3.3 x 10-17 = 2.208 x 10-27J W = hc λo λo =hc W. λo = 6.6 x 10-34 x 3.0 x 108 2.3 x 1.6 x 10-19 λo = 8.61 x 10-7mEVALUATIONIf photon of wave length 2.0 X 1017m is incident on a metal and the kinetic energy of the emitted electrons is 23.5eV . Calculate the work function of the metal. (h = 6.6 x 10-34JS, 1eV = 1.6 x 10-19J, c = 3.0 x 108 ).Determine the threshold frequency of the metal in (1) above, hence explain what will happen if a light of frequency 9.1 x 1022Hz is illuminated on the metal. X RAYX-ray was discovered in 1895 by Williams Rontgen. X – rays are produced when thermally generated electrons from a hot filament are accelerated through a high potential difference and focused on to a tungsten target, where the electrons are suddenly stopped.MODE OF OPERATION In the X- ray tube, a high potential difference is applied between the hot cathode and the anode. Electrons are emitted from the cathode and are accelerated to an extremely high speed. They are abruptly decelerated when they strike the anode causing the emission of high energy radiation of short wavelength i.e X-rays. The anode becomes very hot in the process and requires cooling gins on the outside of the tube.ENERGY CONVERSION DURING X – RAY PRODUCTION During X – ray production, electrical energy is converted to thermal energy. The thermal energy is converted into mechanical energy (kinetic energy) to accelerate the electron. The mechanical energy is converted into electromagnetic energy of the x-ray TYPES OF X – RAYThere are two types of x- raysHard x – rays and 2. Soft x- raysCharacteristics of Hard x-raysHigh penetrating power or ability Shorter wavelengthCharacteristics of soft x –ray.low penetrating powerlonger wavelengthEVALUATIONstate the energy conversions in an x-ray tube.Differentiate between soft and hard x-ray.HARDNESSThis is a measure of the strength or penetrating ability of the x – ray.INTENSITYThis is the energy radiated per unit time per unit area by the x –ray. It depends on the current of the filament .Properties of x- raysX – rays are electromagnetic waves of high frequencyX – rays have short wavelength ( 2 x 10-10m )X – rays have high penetrating powerX-rays travels in straight lineThey are not diffracted by electric or magnetic field.They are not diffracted by crystals.They ionized gasesThey cause zinc sulphide to fluoresce.Application of X – rayFor examining body to locate broken bonesTo detect metals and contra band in a baggageThey are used to detect cracks n welded jointsFor investigating crystal structureTreatment of tumors and malignant growthIt is used in agriculture to kill germs.Hazards of x- raysIt causes genetic mutationIt can destroy body cellsit causes leukemia, by damaging body tissuesit causes skin burns and cancer.PrecautionsThose who work with x-rays should put on lead coat and they should always go for regular medical check-up.GENERAL EVALUATIONWhat is the function of lighting conductorsExplain lightingWEEKEND ASSIGNMENT 1. Which of the following give rise to the line spectra observed in atoms? (a) excitation of electrons in the atom (b) change of an electron from a higher to a lower energy level(c) Distributed photo in the nucleus2. Which of the following is called photo electric effect. (a) two electrons are created from a quantum of light (b) metals absorbs quanta of light and then emits electrons (c) a high energy emits photon as it is slowed down3. The minimum frequency that can cause photo emission of electrons from metal surface is known as (a) wavelength (b) threshold frequency (c) frequency of the incident light4. The maximum kinetic of the photo electrons depend on (a) work function (b) frequency (c) intensity of the incident ray5. The minimum energy required to liberate an electron from a metallic surface is (a) ionization energy (b) work function (c) kinetic energy,THEORY1. (a) explain the terms “ hardness” and “ intensity” as applied to x-ray tube. (b) State three uses of x-raysDetermine the frequency of the photon whose energy is required to eject a surface electron with a kinetic energy of 1.970 x 10-19 eV. If the work function of the metal is 1.334 x 10-19eV.(1eV = 1.6 x 10-19J, h = 6.6 x 10-34Js, C = 3 .0 x 108ms-1)WEEK EIGHTTOPIC: CONDUCTION OF ELECTRICITY IN GASESCONTENTCondition for dischargeCharacteristics of cathode rays and applicationThermionic emission and applicationDiode valve/Cathode rays OscilloscopeCondition for DischargeExperiments with discharge tube show that gases conduct electricity under low pressure and high potential difference. At very low pressure and high voltage, the gas in the discharge tube breaks into ions. The positive ions move towards the cathode, the negative ions and free electrons move towards the anode. The positive ions knocks off electrons from the metal plate of the cathode. The electrons produced at cathode are called cathode rays.EVALUATIONDraw a discharge tube and explain how electricity is conducted through it.What are cathode rays?Characteristics of Cathode raysThey consist of streams of fast moving electrons.They cause glass and other materials to glow or fluoresce with a greenish colour.They travel in straight linesThey are deflected by electric and magnetic field.They can ionize a gasThey will turn a light paddle wheel in the tube because they have mass, momentum and energy.They are highly energetic particles.They can affect photographic platesThey can produce x-rays from high density metals when they are suddenly stopped by such metals.They are highly penetrating and can penetrate through metals such as aluminium, steel and gold foil.Application of Cathode raysOne application of cathode rays is in fluorescent tubes used commercially for lighting and display signs. The tube contain mercury vapour, which at low pressure glow or fluoresce at the passage of cathode rays.EVALUATIONMention at least five characteristics of cathode raysDescribe how cathode rays are used in fluorescent lamp and in the production of neon sign.Thermionic Emission Whenever a metal is heated to a sufficiently high temperature, electrons are emitted from the surface of the metal in a process known as thermionic emission When the filament is heated to a high temperature, extra energy given to its free electrosn at the surface of the metal enables them to break through the surface of the metal and exist outside it as an ‘electron cloud’. This is the process of tehrmionic emission.The diode valve is a simple application of the principle of thermionic emission. It consists of an anode, usually in the form of a cylinder, a hot filament (heater ) made of tungsten wire and components surrounding the filament. All these components parts are enclosed in a highly evacuated glass bulb.Action of a diode, diode characteristicsThe filament supplies free electrons when heated by the current from the battery (E), when the anode is made positive in potential with respect to the cathode, electrons flow towards the anode and constitute the anode current (Ia) which is registered by the milli-ammeter.Diode CharacteristicsDiode characteristics curve shows that diode valve does not obey Ohm’s law . That is why it is called non-Ohmic conductor . Because the action of diode allows current to flow only in one direction, the valve is used as rectifier to produce d.c. voltage from an a.c supply.Cathode Ray OscilloscopeThe cathode rays oscilloscope is an instrument used for the investigation of currents voltages in electronic circuits. It is a vacuum tube containing an electron gun at one end, and a fluorescent screen at the other end. Between these are to pairs of deflector plates near the middle of the tube. The electron gun consists of (i) the heated filament, to supply electrons by thermionic emission, (ii) the anode (iii0 the cathode. The anode acts as focusing lens t o accelerate and focus the electron on to a spot in the fluorescent screen.The cathode rays oscillope is used for studying all types of wave forms especially the alternating current wave forms and to measure frequencies and amplitude of voltage of electronic devices.GENERAL EVALUATIONDefine gravitational potentialDefine gravitational fieldREADING ASSIGNMENT New School Physics for SSS page 481-483.WEEKEND ASSIGNMENT 1. When a metal is heated to a high temperature and electrons are emitted from its surface, this is known as ____ (a) photoelectric emission (b) Thermionic emission (c) field emission(d) secondary emission 2. The term electrical discharge means (a) voltage is a gas (b) current in a liquid ( c) current in a gas (d) voltage in a liquid.3. Which of the following is an application of glow discharge phenomena? (a) filament lamp (b) fluorescent lamp (c) cathode ray oscilloscope (d) electron microscope .4. Which of the following is an application of hot cathode emission. (a) filament lamp (b) cathode ray oscilloscope (c) electron telescope (d) Binoculars5. Which of the following contributed to conduction in a gas? (i) molecules (ii) electrons (iii) ions (A) I only (b) II only (c) I and III only (d) II and III only.THEORY1 (a) Draw a labeled diagram of a cathode ray oscilloscope showing the essential parts (b) What are the functions of: (i) the hot filament (ii) the anode (iii) fluorescent screen (iv) deflector plates(c) State one way in which cathode rays differ from electromagnetic waves2 (a) Describe briefly how electrons can be liberated from i. a cold cathode ii. A hot cathode (b) What is thermionic emission.WEEK NINETOPIC: WAVE – PARTICLES DUALITY (PARADOX)CONTENT Duality of LightDuality of MatterUncertainty Principle.The principle of wave-particle duality explains the dual nature of matter as a wave and as a particle.Duality of LightLight is an electromagnetic wave which radiates out from its source with a velocity of 3 x 108m/s. This can be use to explain the concepts of reflection, refraction and interference. To explain other concepts like emission, absorption, photo electric effect and radiation of energy by heated bodies, it is assumed that light energy travels through space in the form of concentrated bundles of energy called photons. Each photon is assumed to have energy E = hF. According to Planck’s theory H is called Planck constant. Thus, the particle nature of light is highlighted.EVALUATIONBriefly explain the duality of light.Explain three concepts that show the behavior of light as particle.DUALITY OF MATTERNewton’s theories and laws considered matter and electrons as particles. De Broglie postulated that an electron of mass ‘m’ moving with a velocity v radiates energy and has a wavelength, ʎ = h (h = Planck constant). mvThis is true for electrons and other elementary particles like protons and neutrons.EVALUATIONWhat is the energy of a photon whose frequency is 50KHz, given that Planck constant, h= 6.6 x 10-34 Js.A bullet of mass 0.002kg is fired with a velocity of 1000m/s. what is its de Broglie wavelength? Will the wave nature of this mass be observable?UNCERTAINTY PRINCIPLEHeisenberg has shown by this experiment in electron diffraction that it is impossible to know the exact position and velocity of a particle simultaneously. In the experiment, an electron was assumed to be a bundle of waves which extends over a small region x. The exact position of the atom in this bundle and within space s is difficult to know. This uncertainty is called, the uncertainty of indeterminacy.He therefore says that if x is the uncertainty in the position and v the uncertainty in the velocity of a particle, V x > h If P is the momentum, then P = m V :. P X ≥ h . 2∏ E t ≥ h . 2∏ E is the uncertainty in the energy of the particle and t, the uncertainty in time. Hence, this principle is saying that we cannot determine the exact values of these quantities.GENERAL EVALUATIONExplain Heisenberg uncertainty principleState two phenomena that can be satisfactorily explained by assuming that matter behaves like (a) waves (b) particles.WEEKEND ASSIGNMENT1. Which of the following are not complimentary variables (a) Energy and time (b) energy and position (c) Energy and mass (d) Velocity and position .2. The duality of matter implies that matter? (a) Exist as particle of dual composition (b) has momentum and energy (c) has both wave and particle property (d) is made up of dual materials3. According to quantum theory, electromagnetic wave is transmitted in tiny bundles of energy called (a) photons (b) electrons (c) photons (d) protons4. Which of the following scientists proposed the uncertainty principle? (a) De Broglie(b) Heisenberg (c) Newton (d) Lenz5. The uncertainty in the measurement of two complementary variables is ____ (a) ≥ (b) ≥ (c) ≈ (d) = THEORY1. With what fundamental accuracy can the position of a 60g piece of stone be located, if the stone has a speed of 240m/s, accurate to 0.1%.2. (a) State Heisenberg uncertain principle. (b) Mention two phenomena that can be explained in terms of the particulate nature of light.WEEK TENTOPIC: ROCKETS AND SATELLITES (BASIC ELECTRONICS)CONTENTSatellite and their functionsComponents of a satelliteSemiconductors.SATELLITES AND THEIR FUNCTIONSThe word satellite refers to a body orbiting a larger one. There are natural satellites (e.g the Earth and other planets orbiting the Sun), and artificial satellites such as; Communication Satellites (that transmit telecommunication signals), Global Positioning Satellites (that allow for the identification of locations on the Earth) and Meteorological Satellites (that monitor weather and climate patterns). Examples of Nigeria satellite includes; Niger-SAT 1 (a disaster-monitoring microsatellite), NICOM-SAT 1 (for mobile phone and internet services. However due to the failure of its solar cells system, the satellite has ceased to function). COMPONENTS OF A SATELLITEAll satellites have some common basic components that work together to form the following systems; Power generation and distribution systemCommand and data handling systemPayloadProtective shieldingRocket thruster system.Other components include; solar cells, batteries, command antenna, communication antenna, radio receivers and transmitters, rocket fuel, rocket motor, rocket thrusters, cameras.BASIC ELECTRONICS; SEMICONDUCTORSSemiconductors are crystalline or amorphous solids with distinct electrical characteristics.They are of higher of higher resistance than the typical conductors but of lower of lower resistance than the insulators. Their resistance decreases with temperature - a behavior opposite to that of metals.Their conducting properties can be altered in useful ways by the deliberate introduction (‘’doping’’) of impurities into the crystal structure.Doping greatly increases the number of charge carriers (holes and electrons) within the crystal.There are two major types of impurities; the donor and the acceptor. Antimony, Arsenic and Phosphorus are typical donor elements while Aluminum, Boron and Gallium are good acceptors. Addition of donor element produces the n–type semiconductor while the addition of acceptor element results in the p–type semiconductor. The n-type semiconductor contains mostly free electrons, it has excess electrons (i.e its charge carriers are the excess electron), and a p-type semiconductor contains mostly free holes, it has a shortage of electron (i.e its charge carriers are the excess holes).A single semiconductor can have many p- and n- type regions when doped under precise conditions. The junction between these regions are referred to as the p-n junction.Doping lowers the resistance of a semiconductor but also permits the creation of semi-conduction junction. The behavior of charge carriers at this junction is responsible for its usefulness in diodes, transistors and all modern electronics.The most widely used semiconductors are Silicon, Germallium and compounds of Gallium. Elements located where the metalloids are on the periodic table are usually used as semiconductors.GENERAL EVALUATION With the aid of a diagram, describe how continuous current can be generated from mechanical energyWith the aid of a diagram, describe how continuous current can be generated from chemical energy.WEEKEND ASSIGNMENT1. Most satellite depend on ….. for the generation of their electrical energy supply. (a) d.c generators (b) Leclanche cells (c) solar cells (d) hydroelectricity. 2. The following are components parts of a rocket except (a) fins (b) nozzle (c) propellant tank (d) turbine.3. One of the following is a component of a satellite (a) camera (b) fins (c) command antenna (d) solar cells.4. The function of the fins in a rocket is to (a) beautify it (b) make it fly (c) stabilize it and maintain its direction of motion (d) increase its mass.5. What is the function of the power generation and distribution system in a satellite? (a) capturing solar energy and converting it to the electrical energy needed (b) increase the weight of the engine (c) receiving and transmitting of data (d) to beautify the satellite. THEORYDraw a satellite and a rocket, labeling at least five parts on each.What are satellites used for?