scheme for perfect score module 2012

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  2. 2. SECTION II - COMMON MISTAKES AND MISCONCEPTIONS8.Physical QuantityPhysical quantity measuredPhysics Unit and symbolStop watchtime Second. s voltmeterVoltage, VVolt, V thermometertemperatureKelvin or oCelsiusBourdon gaugeGas pressure Pascal, Pa AmmeterElectric currentAmpere, A9. TermsCommon Mistake Correct Answer[The type of energywhen the object is at P]Gravitational Potential Energya Potential energy Force acting on surface area Force/area Normal force acting on a unit ofb Pressuresurface area A product of depth, density and gravitational accelerationPascals principle In a close container, force is In a close container, pressure isc transmitted equallytransmitted equally.Latent heat of Heat absorbed to change 1 kgdHeat absorbed to changevaporization of liquid to gas without any by 1oC changes in temperature.Amount of kinetic energy in aneTransfer from hot body toTemperature object cold body[Physics phenomena ina prism]Total internal reflectionfReflection
  3. 3. Terms Common Mistake Correct AnswerCritical angle is when theCritical angle is the incidentrefracted angle is 90oangle in denser medium whichg Critical angleCritical angle is the incidentproduces when the refractedangle when the reflectedangle in less dense medium isangle is 90o90oThe image that formedThe image that cannotbeh Virtual imagebehind the lensformed on the screen light of one frequency /i Monochromatic light A colour of one light wavelength / colour .. displacement of anyMaximum point of the particle/oscillating system fromj Amplitudehighest displacement its .. ..The time taken for any particlek PeriodOne complete oscillationto make one completeoscillation1000 W of energy is supplied1000 W of energy is consumedSpecification:l when the power supplied isin 1 s when connected to a 240240 V, 1000 W240 V.V power supply.When the current flow A conductor which can producethrough magnetj electromagnetmagnetic field when currentIs a combination of electric passes through it.and magnetic fieldk Beta particlesNegative charge Fast moving electron
  4. 4. B. Misconceptians Examples: Num MisconceptionsCorrectionOil is used in hydraulic jack because it has1.. because it is not easily evaporate.higher boiling pointSnells law state that:The sine of incident2The sine of incident angle = constant angleRefractive The sine of =refracted angle The sine of refractedindex angleContainer AContainer B water Pressure at X = Pressure at Y because X and Y are at the same depth, same3gravitational acceleration and in the same type of liquid that has same density.The force exerted at X > the force exerted at( P = hg)Y because smaller surface area (P = F /A) To increase the efficiency of ac/dc GENERATOR: Generator the current is induced - Use more number of turns to produce stronger magnetic fieldThe ship can float in sea water becausethe total density of the ship is less thanthe density of waterThe buoyant force is equals to the totalweight of the ship The ship can float in sea water because the buoyant force is bigger than the weight of the ship
  5. 5. C. Paper 3 1. Data TabulationTitle - no unitContent-not consistentExample:Common Mistake Correct AnswerElectric Current VoltageElectric Current, I (A) Voltage, V (V)0.10.5 1.5 0.141.5TOV 1 SPM FORMAT SET 14531/2 SECTION AQuestion 5NoAnswer SchemeMarka The force that gravitation exerts upon a body 1b(i)The mass of slotted weigh in Diagram 5.1 > Diagram 5.21b(ii) The nett force in Diagram 5.2 > Diagram 5.1 1b(iii)The acceleration in Diagram 5.2 > Diagram 5.1 1c The greater the nett force , the greater the acceleration 1d(i)Net force in Diagram 5.1 > Diagram 5.31d(ii) The acceleration in Diagram 5.1 > Diagram 5.3 1d(iii)The weight of 20 N in Diagram 5.1 is perpendicular to the tension of the string 1Question 6NoAnswer SchemeMarkDiagram 6.1 : no relative motiona(i)2Diagram 6.2 : there is a relative motiona(ii) Number of turns in Diagram 6.3 > Diagram 6.21b(i)The greater the number of turn of coil, the greater the change in magnetic flux 1The greater the number of turn of coil, the greater the magnitude of inducedb(ii) 1currentc Faradays Law 1When the magnet is pulled away from the coild Reason : the current will flow in such direction that oppose the change that2cause it
  6. 6. Question 7 NoAnswer SchemeMark aDepth of water 1P = hg5 b = 2.5 x 103 x 102 = 2.5 x 104 N m-2 cLess different of water pressure 1Place the water tank P higher than water tank R // use water pump d(i)2It will increase the water pressure // sufficient water supplyBigger base area //thicker wall at the bottom d(ii) 2Less pressure exerted on the ground // could withstand water pressureLow density material // fiber tank d(iii)2Light // can withstand stronger pressureQuestion 8No Answer SchemeMark1.(a)Atmospheric pressure is the weight of the atmosphere on an object 1(b)1. Vacuum pump is used to pump out the air from the suction cup 3 2. Partial vacuum is created in the suction cup 3. Higher atmospheric pressure push the glass sheet onto the suction cup1(c)(i) Low pressure1 (ii)Larger difference in pressure 1 (iii) Big diameter cup1 (iv)Greater force 1(d) Triple cups 1 Greater force 1 R 1 Straw/syringe/siphon/vacuum cleaner 12Question 9 NoAnswer SchemeMark aThe force exerted by the gas molecules onto a unit of surface area 1When temperature increases, the average kinetic energy increases Rate of collision also increaseb4 Rate of change of momentum increase Force exerted on a unit of surface area increaseTemperature of gas : 9.3 > 9.2c5Volume of gas: 9.3 = 9.2
  7. 7. NoAnswer Scheme Mark Reading of pressure gauge : 9.2 < 9.3 Temperature increase, reading of pressure gauge Pressure Law CharacteristicsExplaination Rate of rotation is less // Temperature does notLarge radiusincrease easily Increase the surface area // less pressure Many tyresdProvide a gripping surface10Tyres with treads Prevent from deformation Strong tyreCan withstand high temperatureHigh melting pointQuestion 10No Answer SchemeMark Electromagnetic induction 1ab4 Number of turns of coil : Diagram 10.3 > Diagram 10.4 Speed of magnet : samecDeflection of galvanometer : Diagram 10.3 > 10.45 When number of turns of coil increased, deflection also increased Faradays LawCharacteristicsExplainationCurve magnet Produce radial magnetic fieldStronger magnetProduce stronger magnetic fieldd Replace component X10 Current is induced in one directionwith commutator Good conductorCopper wire coilThick copper wireLess resistance
  8. 8. Question 11(a)Distance between optical centre and focal point(b)(i)M1 correct substitution into formula or correct answer M = v/u = 60/20 = 3(b)(ii) M1 correct substitution into formula:11 11 1= + = + 20 60 M2Answer with correct unit f = 15 cm = 0.15 m(b)(iii)M1: P = 100/f = 100/15M2: Answer with correct unit: = 6.67 D(c)M1: Parallel light rays from the hot sun at infinity pass through a convex lens// labeled diagramM2: Light rays are focused after passing through the lens // labeled diagramM3: Light rays are converged onto a focal point of the lensM4:At the point, the intensity of lights is great (and the light energy) causes an increases in temperature. When the spot on the paper become hot enough, the paper start to burn // light energy change to heat energy.Aspect ReasonFocal length is longer // eyepiece must be more longer focal Low power of eye piecelength than objective lensFocal length is shorter / objective lens must be powerful lens High power objective lensthan eyepiece lens// Objective lens must be shorter focallength than eyepiece lens. Distance between lenses :To produce bigger image from the eyepiece // to increase >fo + fe the magnification Position of the specimen : fo
  9. 9. Question 12Answer:(a) frequency(b) 1 High pitch, high frequency / pitch directly propotional to frequency2 frequency is inversly propotional to wave length // high frequency has shorterwave length3 Short / high f / high pith at C, will diffract / spread out/ bend less4 Sound easily diffracted / bending / spread out during low pitch/ low f/long / at A,B,C(c)Characteristic Reason Large diameter Receive more signal Same as focal length Signal are focused/converged to the receiver Microwave Has high frequency / high energy The signal is not blocked / easy to beHighdetectedChoose K because Because it has large diameter, Same as focal length, use microwave and locate at high position.(d)(i) v = 2s/t = (2 x 90)/0.12 = 1 500 m/s (i) V = f = 1 500/50 000 = 0.03 m = 3 cmTOV 2 SPM FORMAT SET 24531/2 SECTION AQUESTION 5No Answer Scheme MarkaThe size of the coin in Diagram 6.1 < Diagram 6.2 1bRefraction of light wave2 Light travels from water to air // denser to less dense mediumcLight is refracted away from normal line3 The image is seen bigger and closer to the observer eye n = rd/ad = H/hdh = 16/(4/3)2 = 12 cmeUse liquid with bigger refractive index 1
  10. 10. QUESTION 6No Answer SchemeMark 1a(i) Kinetic energy to electric energy Rotating coil will cut the magnetic fluxa(ii)Emf is produced 3 The commutatorwii ensure the current flow in one directionb(i) The ratio Np : Ns is 6 : 11b(ii)diode 1 Capacitorb(iii) 2 Reason : it can store and discharge charges Copper wire // laminated iron corec2 Reason : good conductor // reduce eddy currentQUESTION 7No Answer SchemeMarkaTemperature increases 2Pressure increasesbWhen temperature increases, the average kinetic energy increases3Rate of collision also increaseRate of change of momentum increaseForce exerted on a unit of surface area increase c)P1 = 200 kPaT1 = 273 + 30 = 303 KP2 = 225 kPaT2 = (T1P2)/ P1 = (303 x225) /200 3= 340.875 Kd(i) More1d(ii) Able to support greater mass // heavier load 1d(iii)Grips efficiently1
  11. 11. QUESTION 8No Answ