# skema modul perfect score physics 2012

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1. BAHAGIAN PENGURUSAN SEKOLAH BERASRAMA PENUH SEKOLAH KECEMERLANGAN KEMENTERIAN PELAJARAN MALAYSIA MARKING SCHEME PERFECT SCORE & X A-PLUS MODULE PHYSICS 2012 2. SECTION II - COMMON MISTAKES AND MISCONCEPTIONS 8. Physical Quantity Physical quantity measured Physics Unit and symbol Stop watch time Second. s voltmeter Voltage, V Volt, V thermometer temperature Kelvin or oCelsius Bourdon gauge Gas pressure Pascal, Pa Ammeter Electric current Ampere, A 9. Terms Common Mistake Correct Answer a [The type of energy when the object is at P] Potential energy Gravitational Potential Energy b Pressure Force acting on surface area Force/area A product of depth, density and gravitational acceleration Normal force acting on a unit of surface area c Pascals principle In a close container, force is transmitted equally In a close container, pressure is transmitted equally. d Latent heat of vaporization Heat absorbed to change by 1oC Heat absorbed to change 1 kg of liquid to gas without any changes in temperature. e Temperature Transfer from hot body to cold body Amount of kinetic energy in an object f [Physics phenomena in a prism] Reflection Total internal reflection 3. Terms Common Mistake Correct Answer g Critical angle Critical angle is when the refracted angle is 90o Critical angle is the incident angle when the reflected angle is 90o Critical angle is the incident angle in denser medium which produces when the refracted angle in less dense medium is 90o h Virtual image The image that formed behind the lens The image that cannot be formed on the screen i Monochromatic light A colour of one light light of one frequency / wavelength / colour j Amplitude Maximum point of the highest displacement .. displacement of any particle/oscillating system from its .. .. k Period One complete oscillation The time taken for any particle to make one complete oscillation l Specification: 240 V, 1000 W 1000 W of energy is supplied when the power supplied is 240 V. 1000 W of energy is consumed in 1 s when connected to a 240 V power supply. j electromagnet When the current flow through magnet Is a combination of electric and magnetic field A conductor which can produce magnetic field when current passes through it. k Beta particles Negative charge Fast moving electron 4. B. Misconceptians Examples: Num Misconceptions Correction 1 Oil is used in hydraulic jack because it has higher boiling point .. because it is not easily evaporate. 2 Snells law state that: The sine of incident angle = Refractive indexThe sine of refracted angle The sine of incident angle = constant The sine of refracted angle 3 Container A Container B The force exerted at X > the force exerted at Y because smaller surface area (P = F /A) Pressure at X = Pressure at Y because X and Y are at the same depth, same gravitational acceleration and in the same type of liquid that has same density. ( P = hg) To increase the efficiency of ac/dc GENERATOR: - Use more number of turns to produce stronger magnetic field Generator the current is induced The ship can float in sea water because the buoyant force is bigger than the weight of the ship The ship can float in sea water because the total density of the ship is less than the density of water The buoyant force is equals to the total weight of the ship water 5. C. Paper 3 1. Data Tabulation Title - no unit Content- not consistent Example: Common Mistake Correct Answer Electric Current Voltage 0.1 0.5 0.12 1 0.14 1.5 Electric Current, I (A) Voltage, V (V) 0.10 0.5 0.12 1.0 0.14 1.5 TOV 1 SPM FORMAT SET 1 4531/2 SECTION A Question 5 No Answer Scheme Mark a The force that gravitation exerts upon a body 1 b(i) The mass of slotted weigh in Diagram 5.1 > Diagram 5.2 1 b(ii) The nett force in Diagram 5.2 > Diagram 5.1 1 b(iii) The acceleration in Diagram 5.2 > Diagram 5.1 1 c The greater the nett force , the greater the acceleration 1 d(i) Net force in Diagram 5.1 > Diagram 5.3 1 d(ii) The acceleration in Diagram 5.1 > Diagram 5.3 1 d(iii) The weight of 20 N in Diagram 5.1 is perpendicular to the tension of the string 1 Question 6 No Answer Scheme Mark a(i) Diagram 6.1 : no relative motion Diagram 6.2 : there is a relative motion 2 a(ii) Number of turns in Diagram 6.3 > Diagram 6.2 1 b(i) The greater the number of turn of coil, the greater the change in magnetic flux 1 b(ii) The greater the number of turn of coil, the greater the magnitude of induced current 1 c Faradays Law 1 d When the magnet is pulled away from the coil Reason : the current will flow in such direction that oppose the change that cause it 2 6. Question 7 No Answer Scheme Mark a Depth of water 1 b P = hg5 = 2.5 x 103 x 10 = 2.5 x 104 N m-2 2 c Less different of water pressure 1 d(i) Place the water tank P higher than water tank R // use water pump It will increase the water pressure // sufficient water supply 2 d(ii) Bigger base area //thicker wall at the bottom Less pressure exerted on the ground // could withstand water pressure 2 d(iii) Low density material // fiber tank Light // can withstand stronger pressure 2 Question 8 No Answer Scheme Mark 1. (a) (b) (c)(i) (ii) (iii) (iv) (d) Atmospheric pressure is the weight of the atmosphere on an object 1. Vacuum pump is used to pump out the air from the suction cup 2. Partial vacuum is created in the suction cup 3. Higher atmospheric pressure push the glass sheet onto the suction cup Low pressure Larger difference in pressure Big diameter cup Greater force Triple cups Greater force R Straw/syringe/siphon/vacuum cleaner 1 3 1 1 1 1 1 1 1 1 12 Question 9 No Answer Scheme Mark a The force exerted by the gas molecules onto a unit of surface area 1 7. No Answer Scheme Mark b When temperature increases, the average kinetic energy increases Rate of collision also increase Rate of change of momentum increase Force exerted on a unit of surface area increase 4 c Temperature of gas : 9.3 > 9.2 Volume of gas : 9.3 = 9.2 Reading of pressure gauge : 9.2 < 9.3 Temperature increase, reading of pressure gauge Pressure Law 5 d Characteristics Explaination Large radius Rate of rotation is less // Temperature does not increase easily Many tyres Increase the surface area // less pressure Tyres with treads Provide a gripping surface Strong tyre Prevent from deformation High melting point Can withstand high temperature 10 Question 10 No Answer Scheme Mark a Electromagnetic induction 1 b 4 c Number of turns of coil : Diagram 10.3 > Diagram 10.4 Speed of magnet : same Deflection of galvanometer : Diagram 10.3 > 10.4 When number of turns of coil increased, deflection also increased Faradays Law 5 d Characteristics Explaination Curve magnet Produce radial magnetic field Stronger magnet Produce stronger magnetic field Replace component X with commutator Current is induced in one direction Copper wire coil Good conductor Thick copper wire Less resistance 10 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: M2 Answer with correct unit f = 15 cm = 0.15 m (b)(iii) M1: P = 100/f = 100/15 M2: Answer with correct unit: = 6.67 D (c) M1: Parallel light rays from the hot sun at infinity pass through a convex lens// labeled diagram M2: Light rays are focused after passing through the lens // labeled diagram M3: Light rays are converged onto a focal point of the lens M4: 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 Reason Low power of eye piece Focal length is longer // eyepiece must be more longer focal length than objective lens High power objective lens Focal length is shorter / objective lens must be powerful lens than eyepiece lens// Objective lens must be shorter focal length than eyepiece lens. Distance between lenses : >fo + fe To produce bigger image from the eyepiece // to increase the magnification Position of the specimen : fo< u < 2fo To produce real, inverted and magnified image The most suitable is : microscope M Focal length of eyepiece is longer than objective lens, distance between lenses is greater than (fo + fe), and the position of the specimen is between fo and 2 fo 9. Question 12 Answer: (a) frequency (b) 1 High pitch, high frequency / pitch directly propotional to frequency 2 frequency is inversly propotional to wave length // high frequency has shorter wave length 3 Short / high f / high pith at C, will diffract / spread out/ bend less 4 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 High The signal is not blocked / easy to be detected Choose 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 cm TOV 2 SPM FORMAT SET 2 4531/2 SECTION A QUESTION 5 No Answer Scheme Mark a The size of the coin in Diagram 6.1 < Diagram 6.2 1 b Refraction of light wave 2 c Light travels from water to air // denser to less dense medium Light is refracted away from normal line The image is seen bigger and closer to the observer eye 3 d n = rd/ad = H/h h = 16/(4/3) = 12 cm 2 e Use liquid with bigger refractive index 1 10. QUESTION 6 No Answer Scheme Mark a(i) Kinetic energy to electric energy 1 a(ii) Rotating coil will cut the magnetic flux Emf is produced The commutatorwii ensure the current flow in one direction 3 b(i) The ratio Np : Ns is 6 : 1 1 b(ii) diode 1 b(iii) Capacitor Reason : it can store and discharge charges 2 c Copper wire // laminated iron core Reason : good conductor // reduce eddy current 2 QU

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