PRE-LEAVING CERTIFICATE EXAMINATION, 2012 MARKING SCHEME PHYSICS HIGHER AND ORDINARY LEVEL

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1 *WMS13* PRE-LEAVING CERTIFICATE EXAMINATION, 01 MARKING SCHEME PHYSICS HIGHER AND ORDINARY LEVEL 35 Finglas Business Park, Tolka Valley Road, Finglas, Dublin 11 T: , F: , E: W: Page 1 of 8

2 In considering this marking scheme the following points should be noted: 1. In many instances only key words are given, words that must appear in the correct context in the candidate s answer in order to merit the assigned marks.. Words, expressions or statements separated by a solidus, /, are alternatives which are equally acceptable. 3. Answers that are separated by a double solidus, //, are answers which are mutually exclusive. A partial answer from one side of the // may not be taken in conjunction with a partial answer from the other side. 4. The descriptions, methods and definitions in the scheme are not exhaustive and alternative valid answers are acceptable. 5. The detail required in any answer is determined by the context and manner in which the question is asked and by the number of marks assigned to the answer in the examination paper. Therefore, in any instance, it may vary from year to year. 6. For lack of units, or incorrect units, one mark is deducted, as indicated. 7. Each time an arithmetical slip occurs in a calculation one mark is deducted. Page of 8

3 HIGHER LEVEL Answer three question from Section A and five questions from Section B Section A ( 10 marks ) Answer three questions from this section Each question carries 40 marks 1. A student carried out an investigation in the laboratory to verify the laws of equilibrium for a set of co-planar forces acting on a uniform horizontal metre stick. The weight of the metre stick was found to be 1. N. The experimental arrangement is illustrated below. Note that all the forces are acting perpendicular to the metre stick. Using the information in the above diagram (i) Show that the vector sum of the forces on the metre stick is zero. (6) Upwards force 5. N +3. N = 8.4 N () Downward force 5 N + 1. N +. N = 8.4 N () Since upward = downward the net force is zero () (ii) Show that the sum of the moments of the forces about an axis through the zero mark of the metre stick is zero. (9) Clockwise moments ( ) + ( ) + ( ) = 3. Nm (4) Anticlockwise moments ( ) + ( ) = 3. Nm (4) Since clockwise = anticlockwise the sum of the moments is zero. (1) (iii) By choosing an axis through any point on the metre stick other than zero show that the sum of the moments of the forces is zero. (9) The candidate can repeat a calculation similar to above using any axis and should get that clockwise equals anticlockwise. Similar division of marks State the conclusion that can be drawn from the results of part (i) and (ii) above. (4) the metre stick is in a state of equilibrium. (4) What change would you make to your calculations if the 5. N force was not acting perpendicular to the metre stick. (6) The perpendicular distance could not be measured along the metre stick. It would no longer be 0.16 m as in the above calculation (6) Show with the help of a diagram how the measured upward forces could be applied to the metre stick. (6) Diagram to show a Newton balance attached to the metre stick and the Newton balance is suspended from a retort stand and clamp arrangement Well labelled diagram give full marks. (6) Page 3 of 8

4 . In an experiment to measure the specific latent heat of fusion of ice a student added melting ice to warm water in a copper calorimeter. The following data were obtained. Mass of calorimeter. 60 g Mass of calorimeter and warm water. 96 g Mass of ice g Initial temperature of warm water C Final temperature of water and melted ice. 14 o C Temperature of ice C Using the given data calculate the value of the specific latent heat of fusion of ice. (18) Answer in box equation 6 each line mi l + mi cw q = mw cw q + mc cc q l = l = l = 06. l = 3.17 J kg What is the benefit of the room temperature being 1 C for the experiment? (6) If the room temperature is half way between the initial and final temperature of the experiment then heat gained from surroundings at the start equals the heat lost to the surroundings at the end. (6) If the ice was at 0 5 C initially, how much extra heat would be needed to change it to water at 14 o C. Where might this heat come from? (9) Extra heat = heat energy to raise temperature of ice from -5 to zero = m c q = = 68.5 joules (6) The heat would come from the warm water and calorimeter. (3) 0 If the student was unaware that the ice was initially at 5 C how would the value obtained for the specific latent heat of fusion of the ice be different. (7) The 68.5 joules should have been subtracted from the right hand side of the equation above. Forgetting to do this results in the answer being too large ( albeit by a small amount) (7) specific heat capacity of copper = 390 specific heat capacity of ice = 0 specific heat capacity of water = J kg K ; J kg K 1 1 J kg K 1 1 Page 4 of 8

5 3. A student carried out an experiment to investigate the relationship between the natural frequency of a stretched string and its length. A sonometer was used and the string was subjected to a constant tension of 80 N throughout the investigation. A set of tuning forks was used to supply the forced frequencies applied to the string. The values of frequency f and the values of length l were noted as follows. f / Hz l / cm Explain with the help of a diagram how the data above was obtained (1) Sonometer, fixed bridges, moving bridge, string, paper rider, tuning fork. (6 1 ) How to measure frequency (3) How to measure length (3) Plot a suitable graph on graph paper to show the relationship between the natural frequency of the stretched string and its length. (1) Graph labels 3 points 6 straight line through origin 3 freq / Hz l / cm l m freq / Hz 300 (300) (1.45) l m 1 Page 5 of 8

6 Using the graph (i) Calculate the length of the string corresponding to a frequency of 300 Hz. (ii) Calculate the value of the mass per unit length of the string. (1) (i) When the frequency is 300 Hz the value of reciprocal length is 1.45 Therefore the value of length is 0.70 m (3) (ii) answer in the box each step 3 3 y y1 Step 1: slope of graph = x x 1 = =.5 Step : slope of graph = Step 3: square both sides of f 1 l f = f l therefore f l =.5 = 1 T l m to get f m = = T 4 l f T 4 l m 80 m = 4 (.5) m = 4.51 kg m 4 1 Why would higher frequency tuning forks lead to less accuracy in this experiment? (4) Higher frequency corresponds to smaller values of length and smaller value give greater percentage errors (4) Page 6 of 8

7 4. In an experiment to calculate the resistivity of a wire a student measured the diameter of the wire five times at different points along the wire. The values noted were 0.7mm, 0.68 mm, 0.73 mm, 0.71mm and 0.68 mm. When fully closed the micrometer used to measure the diameter was reading 0.06 mm. The resistance of the wire was noted as 3.Ω and the length of the wire was 8 cm. What was the purpose of measuring the diameter five times? (6) Diameter may be non uniform () Several measurements gives an average value () This gives better accuracy () What is the reading of the micrometer shown in the picture above if the scale is calibrated in mm? (4) 7.4 mm (4) Calculate the average value of the diameter of the wire from the above data. (6) ( ) 5 = 0.7 mm (6) Calculate the value of the resistivity of the wire. (1) Answer in box equation 3 correct substitution 3 finish 6 r r r A R p r R = = l p = = 1.5 Ω m 3 (0.35 ) 3. l What precautions should you take to improve the accuracy (i) in the measurement of the length of the wire and (ii) in the measurement of the resistance of the wire? (8) (i) Avoid the error of parallax (4) (ii) Check ohmmeter for a zero error etc (4) Why do energy companies need to know the resistivity of the wire they use to transmit electrical energy? (4) The loss of power when transmitting is related to the value of resistivity (4) Page 7 of 8

8 Answer five questions from this section Each question carries 56 marks Section B ( 80 marks ) 5. Answer any eight of the following parts (a), (b), (c) etc. (a) A cyclist exerts a force of 50N on each of the two handlebars of a bicycle and the distance between the handlebars is 50cm. Calculate the torque on the handlebars. (7) Torque = = 5 N m (7) (b) State Hooke s law. (7) (c) Usual (7) The sound intensity level in a room was increased by 6 db. What was the corresponding increase in sound intensity? (7) The sound intensity increased by a factor of 4 (7) (d) Calculate the critical angle for a transparent material of refractive index 1.8. (7) Answer in box (7) 1 sin C = = C = (e) State the three factors upon which the capacitance of a parallel capacitor depends. (7) Common area, permittivity distance between plates,, 3 (f) Explain why a ring circuit for electrical sockets in the home reduces the risk of the wires overheating while carrying current. (7) Current takes two paths to socket reducing the current in each path (7) (g) A refrigerator uses a heat pump. What is the principle of a heat pump? (7) Transfers heat from a cooler region to a warmer region. (7) (h) Calculate the emf induced in a coil of turns if the magnetic flux changes from 6 Wb to Wb in a time of 4 ms. (7) Answer in box (7) dφ 4 emf = N = 5000 = volts 3 dt 4 (i) Which of the three types of radiation a, b or g is the most ionising? (7) Answer is a (7) (j) Give the quark composition of the proton Uud (7) Or Explain the difference between a diode in forward bias and a diode in reverse bias (7) Forward bias the diode conducts, reverse bias diode does not conduct (7) Page 8 of 8

9 6. State (i) the principle of the conservation of energy (ii) the principle of the conservation of momentum. (1) Usual 6 and 6 A sphere of mass kg is attached to a string of length 3 m. The sphere is pulled to one side so that the string makes an angle of 60 0 to the vertical. The sphere is released and it swings down and hits a stationary block of mass kg on a smooth horizontal table. The sphere stops moving on impact and the block moves to the right. Calculate (i) the speed of the sphere at the moment of impact (9) Answer in box get h 3 equation 3 finish 3 h = 3 3cos 60 = 1.5m v = g h = v = 5.4 ms (ii) the speed of the block immediately after impact. (9) Answer in box equation 3 substitute 3 finish 3 mu + 0 = 0 + m v = v ms = v The speed of the block is rounded to the nearest whole number. The motion of the block is now recorded with a data logger. The following is noted. The block moves at a uniform speed for 3 seconds. The block then accelerates uniformly at ms for 5 seconds. The block then moves at a uniform speed for half a minute. The block then decelerates to rest is 8 seconds. Page 9 of 8

10 (i) draw a velocity-time graph to represent the motion of the block (9) answer in box labels for axes 3 correct shape 6 (ii) (iii) Use the velocity-time graph to calculate the distance travelled by the block while being analysed by the data logger. (1) Distance = area under the graph = = = 407 m (1) Draw a diagram to show the surface along which the block moved to record the data above. (5) Answer (5) Level..down level up 7. State the laws of reflection (6) Usual statement Show by means of ray diagrams (i) the formation of a virtual image in a concave mirror and (ii) the formation of an image in a convex mirror. (18) Answer in box (i) object inside f 3 correct rays 3 Correct location of image 3 Page of 8

11 (ii) correct location of object 3 correct rays 3 Correct location of image 3 Why does a dentist use a concave mirror to view a cavity in a tooth rather than a plane mirror? (6) To get a magnified image of the tooth 6 Why is a convex mirror used as the rear view mirror in a car? (6) Gives a large field of vision 3 Image is upright ( erect ) 3 An object of height 5 cm is placed 90 cm in front of a convex mirror of focal length 30 cm. Calculate the position and size of the image formed. (1) Answer in box convex = u v f = v =.5cm position 90 v 30 v image size mag. = = u object size.5 x = x = 1.5cm size of image 90 5 Most torches contain a concave reflector. Explain with a diagram the purpose of this reflector. (8) Diagram to show light from bulb (positioned at the focal point of reflector) falling on reflector and 3 leaving as a parallel beam heading for infinity. 3 Page 11 of 8

12 8. Define electric field strength and give its unit. (6) Usual answer 6 Why does charge reside on the outside of a conductor? Outline an experiment to demonstrate that charge resides on the outside of a conductor. (15) Charges repel each to move as far away as possible 3 Diagram 3 Procedure 6 Conclusion 3 Point action is due to the accumulation of charges at a sharp point on a conductor. Explain how point action contributes to the operation of a lightning conductor placed on the roof of a tall building. (9) Emphasis on accumulation of charge at sharp point 4 Leading to lightning heading for sharp point or ionising surrounding air 5 It is generally considered unwise to play golf on a day when thunder storms are expected. Give a reason based on electricity theory why this is so. (5) Golf club acts as a lightning conductor 5 A metal sphere of diameter 30 cm has a charge of 3 mc spread evenly on its surface. Calculate (i) The electric field strength at the surface of the sphere (ii) The electric field strength 7 cm from the surface (iii) The force on a 4 m C point charge placed 7 cm from the surface of the sphere. (1) Answer in box (i) E E 3 q 3 = = 4pe d 4p = NC 9 1 (ii) E 3 3 = = p (iii) NC F = E q = =. N Page 1 of 8

13 9. What are X-rays and name the scientist credited with their discovery. (1) Electromagnetic waves of very short wavelength / very high frequency 6 W Rontgen 6 Outline with the help of a labelled diagram how x-rays are made. Comment on the suitability of a metal that may be used to produce the X-rays. (1) Diagram to show heated cathode/ vacuum/ high voltage/ cooling/.. any three metal has high melting point etc 3 Give a brief description as to what happens inside an atom when X-rays are made.(6) Electrons knocked out of orbit Electrons moving to lower energy levels Photon emitted = + X-rays are used to examine bone structure in the human body. Distinguish between the intensity of an X-ray beam and the penetrating power of an X-ray beam. (8) Intensity number of x-rays / temperature of heater any one for 4 Penetration.. energy of x-ray / voltage setting any one for 4 Give two other uses for X-rays apart from examining bone structure. (6) Locating flaws in metals / examine organs eg lungs /. Any two for Calculate the minimum wavelength of x-rays produced when the accelerating voltage is V. (1) Answer in box equation 3 substitute 6 finish 3 hc hc qv = l = l qv l = = m Page 13 of 8

14 . Answer either part (a) or part (b). (a) In 193 Cockcroft and Walton carried out an experiment in which they bombarded lithium with high energy protons. The nuclear reaction resulted in the production of two a - particles. (i) Outline with a labelled diagram the details of their experimental arrangement. (9) Source of protons / acceleration of protons / lithium target / emitted alphas Scintillation on screen. Minus for each omission (ii) Write a nuclear equation for the reaction. (6) Answer in box Li + 1 H He + He + Energy (iii) How did they detect the a - particles that were produced (6) Scintillation 3 on fluorescent screen 3 (iv) Calculate the energy released in the reaction. (1) Answer in box getting mass change 6 getting energy 6 Mass before reaction = Mass after reaction = Change in mass = = kg = 9 8 Energy released = m c = 3.04 ( 3 ) kg kg Energy released = Joule (mass of proton = kg; mass of lithium nucleus = kg; mass of α-particle = kg; speed of light, c = m s 1 ) The success of Cockcroft and Walton resulted in other research scientists improving the design of particle accelerators. One type of accelerator uses very strong magnetic fields to force charged particles to travel in circular motion. Having been accelerated to very high speeds the particles are often arranged to collide. These collisions may result in the making of new particles. Give the name of three new particles and state their charge (6) Any correct particles with their charge + + Why does a high speed charged particle travel in a circular motion when it enters a magnetic field? (5) Force of magnetic field is perpendicular to velocity of particle Electrons enter a magnetic field travelling with a speed of 9. ms. The magnetic flux density of the magnetic field is 3 kt. Calculate the radius of the circular orbit that the electron follows. Assume that the electron travels perpendicular to the direction of the magnetic field. (1) 19 ( charge on electron = 1.6 C ; mass of electron = Answer in box equation 3 substitute 3 finish kg ) Bqv = m v r r mv = = Bq = m Page 14 of 8

15 (b) (i) (ii) (iii) The diagram above shows the various parts of an a.c generator. Why is a voltage induced in the coil? (6) Coil experiences a change in magnetic flux 6 Draw a graph of the induced voltage as a function of time (6) Labels 3 correct shape 3 State three factors that determine the magnitude of the induced voltage (9) Magnetic flux density 3 / speed 3 / number of turns of coil 3 An induction coil was invented by N Callan, an Irish scientist working in Maynooth University. Draw and label a diagram of an induction coil. (1) Primary / secondary/ low voltage source/ make brake facility / high voltage 3 4 for each one Give a use for an induction coil. (6) Produce a high voltage from a dc supply Transformers are used to increase the voltage of an a.c supply. Why do transformers work for a.c. and not for d.c. (6) They need a change in magnetic flux 6 Energy companies transmit electricity at very high voltages even though these high voltages are dangerous. What is the reason for the high voltages? (5) High voltage means low current means huge saving on energy losses as heat 5 Give two factors that lead to energy losses in transformers. (6) Ohmic resistance in coils / heat / hysteresis / any two Page 15 of 8

16 11. Read the following passage and answer the accompanying questions While preparing for a school debate on the advantages and disadvantages of nuclear power a student wrote down the following points. Advantages: Almost 0 emissions (very low greenhouse gas emissions). They can be sited almost anywhere unlike oil which is mostly imported. A small amount of matter creates a large amount of energy. A lot of energy is generated from a single power plant. A nuclear aircraft carrier can circle the globe continuously for 30 years on its original fuel while a diesel fuelled carrier has a range of only about 3000 miles before having to refuel. Disadvantages: Nuclear plants are more expensive to build and maintain. Proliferation concerns - breeder reactors yield products that could potentially be stolen and turned into an atomic weapon. Waste products are dangerous and need to be carefully stored for long periods of time. The spent fuel is highly radioactive and has to be carefully stored for many years or decades after use. This adds to the costs.. Nuclear power plants can be dangerous to its surroundings and employees. It would cost a lot to clean in case of spillages. There exist safety concerns if the plant is not operated correctly or conditions arise that were unforeseen when the plant was developed, as happened at the Fukushima plant in Japan; the core melted down following an earthquake and tsunami the plant was not designed to handle despite the world s strongest earthquake codes. (a) What is the difference between nuclear fission and nuclear fusion? (7) Clear distinction eg two definitions 7 (b) Why is nuclear fusion not used at present to generate energy for commercial use? (7) Difficulty in controlling high temperature 7 (c) Nuclear fission reactors can use enriched uranium as a fuel. What is enriched uranium? (7) Increase in the % of the uranium (d) What is the purpose of the moderator in a thermal nuclear reactor (7) Slows the neutrons down to a speed suitable for further fission 7 (e) A nuclear reactor is just a big kettle. What is the justification for such an apparently strange comment? (7) Reactors used to boil water to produce steam to turn turbine 7 (f) Calculate the decay constant for a substance whose half- life is hours (7) Answer in box 7 (g) l ln = = s 5 1 In the following nuclear reaction the mass of each deuterium nucleus has a value of kg and the mass of the helium nucleus is kg. E is the energy released in the reaction. Calculate the value of E. ( c = 3 8 ms 1 ) 4 1 H + 1H He + E (7) Answer in box 7 Page 16 of 8

17 m total mass before reaction = = r 7 7 Total mass after reaction = Change in mass = m = E = mc = E = kg 7 8 joule (h) Give two sources of background radiation. (7) Radon / uranium deposits in earth/ cosmic radiation/ nuclear bomb testing Any two Answer any two of the following parts (a), (b), (c), (d) (a) State Newton s universal law of gravitation. (6) Usual statement 6 To a reasonably good approximation the earth orbits the sun in a circular orbit. Given that the mass of the sun is G c h kg, that the radius of the orbit is 1.5 m and that 11 = 7.6 N m kg, calculate (i) The linear speed of the earth (ii) The angular speed of the earth (iii) The period of the orbit. (18) Answer (i) equation substitute finish v = G M R 6.7 v = v =.99 ms (ii) equation substitute finish 4 v.99 w = = = R 1.5 (iii) equation substitute finish T rad s 7 1 p p = = = w Explain why the mass of the earth is not needed for these calculations. (4) The mass of the earth appears on both sides of the equation and cancels 4 7 s Page 17 of 8

18 (b) Explain with the help of a diagram the Doppler effect () Usual explanation A train s whistle emits a continuous note of frequency 640 Hz as it approaches a person standing near the track. To the person the frequency appears to be 70 Hz. Calculate the speed of the train. () Answer equation 3 substitute 3 finish 4 c u = 340 u = f o = fs c fo u = = u ms = u fs c c u Explain in terms of both frequency and wavelength how you can tell whether a distant star is travelling to or from the earth by examining the light from the star. (8) To the earth frequency increases wavelength decreases Away from earth.frequency decreases wavelength increases ( speed of sound in air = 1 340ms ) (c) What is (i) current (ii) resistance (6) Usual definitions Calculate (i) The total resistance of the five resistors. (ii) The total current flowing from the 1V battery. (iii) The current flowing through the Ω resistor. Page 18 of 8

19 Answer (i) R R = 5 + = 3 Ω and R R = = 11 Ω Total resistance = (ii) 1 + = 4.44Ω I V 1 = = =.71 A R 4.44 (iii) voltage 4 current 3 1 Voltage loss across the three resistor = I R =.71 =.96V 11 V.96 Current through ohms = 1.48A R = = (d) Name the Irish scientist who gave the electron its name in the nineteenth century. (6) G J Stoney 6 Distinguish clearly between thermionic emission and photoelectric emission in relation to the electron. (6) Thermionic.. heat 3 Photoelectric light 3 Give a brief outline including diagrams of how you might demonstrate either thermionic emission or photoelectric emission in the laboratory. () Suitable diagram 3 Source of heat or light 3 Method of detecting emitted electrons eg current 4 Why did Einstein s explanation of photoelectric emission caused quite a sensation when it was first published. (6) It suggested that light was not a continuous wave but consisted of bundles of energy i.e. photons Page 19 of 8

20 Ordinary LEVEL Answer three questions from Section A and five questions from Section B Answer three questions from this section. Each question carries 40 marks. Section A 1. A student performed an experiment in the laboratory to measure the acceleration due to gravity using a free fall technique. The following data was recorded. Distance / m Time / s (i) Using this data fill in the following table into your answer booklet. Round off the values to two places of decimals when you have squared the time. Answer 1 mark 1 distance / m time / s (1) (ii) Plot a graph on graph paper of the data. Plot the values of ( distance )on the y-axis ant the values of time on the x-axis. (1) Each point plotted correctly 6 (iii) Calculate the slope of the straight line graph that you obtained. Comment on the value that you get for the slope. (9) The value of the slope is This is then value of g 3 (iv) Draw and label a diagram of the experimental arrangement. (7) Any suitable diagram 4 each label 1 3 ( max of 3 ) y y1 ( Slope of a line = x x 1 ) Page 0 of 8

21 . A student investigated the variation of the fundamental frequency f of a stretched string with its length l and obtained the following data. The student used a sonometer and a set of tuning forks of known frequency. l / m f / Hz (i) Using this data fill in the following table into your answer booklet. Round off the values to two places of decimals when you have found the reciprocal of the values of length. f / Hz 1 / m 1 l Answer Each reciprocal 6 = (1) (ii) Plot a graph on graph paper of the data. Plot the values of frequency on the y-axis ant the values of 1 on the x-axis. (1) Answer each l point plotted correctly marks (iii) The graph that you obtain is a straight line passing through the origin. Comment on the significance of this. (6) Frequency is proportional to reciprocal length or Frequency is inversely proportional to length 6 (iv) Draw and label a diagram of the experimental arrangement. () Sonometer / tuning fork / string / weights for tension / bridges / paper rider 5 3. You have been asked to do an experiment to measure the focal length of a concave mirror. (i) List three pieces of equipment that you might use for the experiment (9) Light box / screen / mirror / metre stick any three 3 3 (ii) Draw and label a diagram of the experimental arrangement. (9) Diagram to show the above 3 3 (iii) State clearly what measurements you would take in the experiment. (6) Object distance u.source to back of mirror 3 Image distance v screen to back of mirror 3 (iv) State three precautions you should take to improve the accuracy of your work (9) Dark room / avoid error of parallax / avoid small measurements.. any three 3 3 (v) Could you use the same experimental method to find the focal length of a convex mirror? Give a reason for your answer. (7) No. 4 image is virtual.3 Page 1 of 8

22 4. A student performed a experiment to measure the resistivity of a wire in the laboratory. The following data was recorded. Length of wire = 1. m Resistance of wire = 3 Ω Diameter of the wire = 1.6 mm. (i) (ii) Name the instrument in the photograph that is used to measure the diameter of the wire. Give a precaution that could be taken when using this instrument to improve the accuracy of the final calculation. (9) Micrometer 3 slip control / zero error / etc any one 6 Name the instrument that is used to measure the length of the wire. Give two precautions that could be taken when using this instrument to improve the accuracy of the final calculation. (9) Metre stick 3 error of parallax / small measurements /..etc 3 (iii) Name the instrument that is used to measure the resistance of the wire. Give a precaution that could be taken when using this instrument to improve the accuracy of the final calculation. (6) Ohmmeter 3 zero error etc.3 (iv) Using the value for the diameter calculate the radius of the wire and express you answer in metres. (4) Radius = 0.8 mm = 4 8 m 4 (v) Calculate the cross-sectional area of the wire using area = Answer in box substitute 3 finish 3 p (8 ) =.01 m 4 6 p r (6) A (vi) Calculate the resistivity of the wire using resistivity = ( A = cross-sectional area; R = resistance; l = length ) l Answer in box substitute 3 finish 3 R (6) A R r = = l = 5 Ω m Page of 8

23 Answer five questions from this section Each question carries 56 marks Section B ( 80 marks ) 5. Answer any eight of the following parts (a), (b), (c) etc. (a) What is a vector quantity and give two examples? Magnitude direction examples and 1 (b) State the law of the conservation of energy Usual 7 (c) Calculate the speed of a wave of frequency 50 Hz and wavelength 5 m ms 7 (d) Name two examples of electromagnetic waves that are not visible to the human eye Any two 3 and 4 (e) (f) (g) (h) (i) (j) What is the purpose of a capacitor? Store electrical energy 7 What is the use of as rheostat in an electrical circuit? Vary current 7 Give an example of latent heat. Any suitable example 7 Name the method of heat transfer that brings the heat of the sun to earth Radiation 7 What is the photoelectric effect? Usial definition 7 A radioactive material has a half life of 5 days. What percentage of a given sample of the material will still be radioactive after 0 days? Start 0% 5 days 50% days...5% 15days...1.5% 0 days 6.5% 7 Award marks for the best eight answers Page 3 of 8

24 6. State Newton s three laws of motion (1) Usual 4 3 Using the ideas of Newton s three laws (i) What is needed to make a stationary object move? A force 6 (ii) Calculate the mass of an object accelerating at 5ms when subjected to a force of 0 N. 0 kg 6 (iii) Give an example of a reaction force. (18) Any suitable example 6 A hail stone falls from rest at a height of 000 m above ground level. If the value of the acceleration due to gravity is 9.8ms calculate the speed of the hail stone just before it hits the ground. (1) Answer in box equation 3 substitute 3 finish 6 u = v = a s = = 0???? 9.8ms 000 m v = u + gs v = + v = v = 0 (9.8) ms t =? The answer you get is bigger than you would expect. Give a reason for this. (6) Air resistance not taken account of 6 If the mass of the hailstone is grams calculate the momentum of the hail stone just before it hits the ground. (8) Momentum = = kg m s (a) Show by means of suitable diagrams how a ray of light refracts as it passes through (i) a diverging lens (ii) a converging lens (iii) a rectangular block (iv) a prism (4) (i) rays from labelled object.3 rays to form labelled image.3 (ii) rays from labelled object.3 rays to form labelled image.3 (iii) ray entering block.. Ray refracted within block.. Ray emerging from block (iv) incident ray could be either white light or monochromatic.. Deviation and/or dispersion within prism.. Refraction as ray/rays exit prism.. Page 4 of 8

25 (b) (c) When the source of a wave moves towards a stationary observer and then passes by the observer changes in the wave will be noticed. (i) what type of changes would be noticed? Change in wavelength / frequency. 6 (ii) how would this affect a sound wave Different pitch 6 (iii) how would this affect a light wave. (18) Different colour.. 6 An echo is an example of the reflection of a sound wave. How would you demonstrate the reflection of a sound wave in the laboratory. (8) Standard demonstration experiment.diagram/ procedure/conclusion 8 A person stands at a distance from a cliff face and shouts loudly. If they hear their echo 4 seconds later how far are they from the cliff face if the speed of sound in air is 1 340ms. (6) Distance = 340 = 680 m if 4 is used instead of deduct 3 marks 8. The diagram below shows a simplified drawing of a spectrometer that you might use in the laboratory to study the nature of light. Label 4 is pointing to a vernier scale. Identify the other four labels. (1) 1=collimator =telescope 3 = table 5= slit control What is the purpose of the vernier scale. (6) Accurate measurement of angular/position 3+3 Show with the help of labelled diagrams what happens when (i) a monochromatic light beam and (ii) a beam of white light pass through a diffraction grating. (1) Usual diagrams (i) diffraction and interference 3+3 (ii) diffraction and interference and /or dispersion A diffraction grating has a grating constant of m. When a ray of light passes through the diffraction grating the angle of diffraction for the first order image is Calculate the wavelength of light. (9) Answer in box equation / substitute / finish l = sin l = 5.85 m What is meant by the polarisation of light? Usual..6 How would you demonstrate polarisation of light in the laboratory? Pass light through a sheet of Polaroid and then a second sheet.8 Give an everyday example of the use of the polarisation of light. (17) Sunglasses 3 Page 5 of 8

26 9. Different materials can conduct an electric current. What is an electric current? (6) Usual definition 6 The current flowing through a material can depend on the voltage applied across the material. We often draw current voltage graphs to illustrate this. Draw a current voltage graph for (i) a metallic conductor at a fixed temperature (ii) an ionic solution with active electrodes (iii) an ionic solution with inactive electrodes (iv) (v) a gas a vacuum. In each name the charge carrier. (30) Label axes.. correct shape.3 charge carrier.1 Same for al five cases A student noted that the resistance of a particular resistor was Ω. What current would flow through the resistor if it was connected to a 6 V battery. 0.6 amp..6 It would be dangerous to connect this resistor across a mains voltage supply. In theory what current might you expect to flow from the mains voltage of 30 V. 3 amp.3 In practice you would most likely not get this current. Explain why. (15) Fuse blows / wire overheats.etc.6 Give one safety device that is used to protect people from the dangers of electricity in the home (5) Any valid answer..5. What are X-rays and name the scientist credited with their discovery. (1) Electromagnetic waves of very high frequency / very small wavelength 6 Rontgen 6 Outline with the help of a labelled diagram how x-rays are made. Comment on the suitability of a metal that may be used to produce the X-rays. (1) Diagram to include heated cathode / anode / high voltage / vacuum Any three Suitable metal high melting point / tungsten 3 Name two uses of X-rays. (6) Any valid uses How can X-rays be harmful to humans and what type of protection is taken by people who are exposed to X-rays? (1) Cause cancer etc 6 Protective clothing / lead apron 6 Nuclear radiation is radiation emitted from the nucleus of an atom. Name the three types of nuclear radiation. (9) Alpha beta gamma the Greek letters will suffice Give one beneficial use of nuclear radiation (5) Any valid answer..5 Page 6 of 8

27 11. Read the following passage and answer the accompanying questions The traditional thermometer is a glass tube with a bulb at one end containing a liquid which expands in a uniform manner with temperature. The tube itself is narrow (capillary) and has calibration markings along it. The liquid is often mercury, but alcohol thermometers use a coloured alcohol. Medically, a maximum thermometer is often used, which indicates the maximum temperature reached even after it is removed from the body. To use the thermometer, the bulb is placed in the location where the temperature is to be measured and left long enough to be certain to reach thermal equilibrium typically three minutes. Maximum-reading is achieved by means of a constriction in the neck close to the bulb. As the temperature of the bulb rises, the liquid expands up the tube through the constriction. When the temperature falls, the column of liquid breaks at the constriction and cannot return to the bulb, thus remaining stationary in the tube. After reading the value, the thermometer must be reset by repeatedly swinging it sharply to shake the liquid back through the constriction. Since compact and inexpensive methods of measuring and displaying temperature became available, electronic thermometers (often called digital, because they display numeric values) have been used. Many display readings to great precision (0.1 C ) but this should not be taken as a guarantee of accuracy: specified accuracy must be checked in documentation and maintained by periodical recalibration. A typical inexpensive electronic ear thermometer for home use has a displayed resolution of 0.1 C, but a stated accuracy within ±0. C when new. [1] (a) What is temperature? Measure of hotness or coldness of a body.7 (b) What is heat? A form of energy..7 (c) What disadvantage is there to using mercury in a thermometer? Dangerous material etc 7 (d) Why is the thermometer placed in the location where the temperature is to be measured for a few minutes? To reach thermal equilibrium ( idea expressed in simple language is fine).7 (e) A thermometer has calibration markings along it. Name another device which has calibration markings along it. Any suitable answer 7 (f) Why are electronic thermometers called digital thermometers? They display numerical values (g) Temperature is often expressed in degrees Celsius. What is the other unit of temperature commonly used in physics? Kelvin.7 (h) What is the value of normal body temperature for humans? (8 7) 37 0 C 7 Page 7 of 8

28 1. Answer any two of the following parts (a), (b), (c), (d). (a) (b) Draw a velocity time graph to illustrate (i) A car starting from rest and undergoing uniform acceleration (ii) A car travelling at a uniform speed (iii) A car undergoing uniform deceleration with a final speed of zero. (18) Labels.. correct shape..4 Describe a practical way of measuring the speed of a trolley as it moves along a table in the laboratory. () Any valid method..diagram.3 Explain 3 Speed = distance time.4 Draw and label a diagram of a gold leaf electroscope. What is the purpose of a gold leaf electroscope (15) Metal cap / metal rod / insulator / metal box / gold leaf any three 3=3+3 Purpose detect / measure charge or voltage. 6 Electric field lines are associated with electric charges. Outline how you would demonstrate electric field patterns in the laboratory. (13) Semolina / beaker of oil / high voltage / plates any three ++ Explain 4 Conclusion 3 (c) What is electromagnetic induction? (6) Usual definition..6 Outline a demonstration of electromagnetic induction (9) Diagram.. 3 Explain. 6 A student wearing wire framed glasses claims that he can generate an electric current in the wire frames by simply moving his head from side to side. How might his claim be correct and why would it be difficult to verify his claim? Wire frames form a coil..3 Moving in earth s magnetic field gives a change in magnetic flux..4 Verify..emf would be very small..6 (13) (d) What is the difference between nuclear fission and nuclear fusion? (1) Two definitions..each.6 Name a material that is used in nuclear fission and give a use for nuclear fission (9) Uranium.3 Generate electricity / bombs 6 What condition is required for nuclear fusion to happen? (7) Very high temperature..7 Page 8 of 8