AQA A-LEVEL PHYSICS 7408/3A Paper 3 Section A Question Paper + Mark scheme [MERGED] June 2022 *JUN2274083A01* IB/M/Jun22/E8 7408/3A For Examiner’s Use Question Mark 1

AQA A-LEVEL PHYSICS 7408/3A Paper 3 Section A Question Paper + Mark scheme [MERGED] June 2022 *JUNA01* IB/M/Jun22/E8 7408/3A For Examiner’s Use Question Mark 1 2 3 4 TOTAL Materials For this paper you must have: • a pencil and a ruler • a scientific calculator • a Data and Formulae Booklet • a protractor. Instructions • Use black ink or black ball-point pen. • Fill in the boxes at the top of this page. • Answer all questions. • You must answer the questions in the spaces provided. Do not write outside the box around each page or on blank pages. • If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s). • Do all rough work in this book. Cross through any work you do not want to be marked. • Show all your working. Information • The marks for questions are shown in brackets. • The maximum mark for this paper is 45. • You are expected to use a scientific calculator where appropriate. • A Data and Formulae Booklet is provided as a loose insert. Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature I declare this is my own work. A-level PHYSICS Paper 3 Section A Time allowed: The total time for both sections of this paper is 2 hours. You are advised to spend approximately 70 minutes on this section. 2 *02* IB/M/Jun22/7408/3A Do not write outside the Section A box Answer all questions in this section. 0 1 Figure 1 shows apparatus used to measure the speed of sound in a steel rod. Figure 1 The steel rod is suspended from a beam using rubber bands. When the hammer is in contact with the end L of the steel rod, a circuit is completed and the signal generator is connected to the oscilloscope. Figure 2 shows the waveform then displayed on the oscilloscope. 3 *03* Turn over ► IB/M/Jun22/7408/3A Do not write outside the Figure 2 box 0 1 . 1 Which control on the oscilloscope should be used to centre the trace vertically on the screen? Tick () one box. [1 mark] X-shift Y-gain Y-shift Question 1 continues on the next page 4 *04* IB/M/Jun22/7408/3A Do not write outside the When the hammer box hits end L, a sound wave travels along the steel rod and is reflected at end R. When the wave returns to L the rod bounces away from the hammer and the circuit is broken. Figure 3 shows the waveform produced by the brief contact between the hammer and L. Note that the waveform has now been centred vertically. Figure 3 Figure 4 shows the time-base setting of the oscilloscope. Figure 4 5 *05* Turn over ► IB/M/Jun22/7408/3A Do not write outside the 0 1 box . 2 The distance between L and R in Figure 1 is 0.870 m. Deduce the speed of sound in the steel rod. [3 marks] speed of sound = m s−1 0 1 . 3 A student repeats the experiment using a steel rod of twice the length. Explain: • how using the longer rod affects the waveform displayed • any changes needed to get an accurate result for the speed. You should include numerical detail. [4 marks] 8 6 *06* IB/M/Jun22/7408/3A Do not write outside the 0 2 box Figure 5 shows a strip of steel of rectangular cross-section clamped at one end. The strip extends horizontally over the edge of a bench. Figure 5 7 *07* Turn over ► IB/M/Jun22/7408/3A Do not write outside the 0 2 box . 1 A mass m is suspended from the free end of the strip. This produces a vertical displacement y. A student intends to measure y with the aid of a horizontal pin fixed to the free end of the steel strip. She positions a clamped vertical ruler behind the pin, as shown in Figure 6. Figure 6 Explain a procedure to avoid parallax error when judging the reading indicated by the position of the pin on the ruler. You may add detail to Figure 6 to illustrate your answer. [2 marks] Question 2 continues on the next page 8 *08* IB/M/Jun22/7408/3A Do not write outside the 0 2 box . 2 It can be shown that 3 3 4mgL y Ewt = where: L is the distance between the free end of the unloaded strip and the blocks w is the width of the strip and is approximately 1 cm t is the thickness of the strip and is approximately 1 mm E is the Young modulus of the steel. A student is asked to determine E using the arrangement shown in Figure 5 with the following restrictions: • only one steel strip of approximate length 30 cm is available • m must be made using a 50 g mass hanger and up to four additional 50 g slotted masses • the experimental procedure must involve only one independent variable • a graphical method must be used to get the result for E. Explain what the student must do to determine E. [5 marks] 9 *09* Turn over ► IB/M/Jun22/7408/3A Do not write outside the box Turn over for the next question 7 10 *10* IB/M/Jun22/7408/3A Do not write outside the 0 3 Conductive putty can easily be formed into different shapes to investigate the effect of box shape on electrical resistance. 0 3 . 1 A student uses vernier callipers to measure the diameter d of a uniform cylinder made of the putty. Suggest one problem with using callipers to make this measurement. [1 mark] 0 3 . 2 Table 1 shows the calliper measurements made by a student. Table 1 d1 / mm d2 / mm d3 / mm d4 / mm d5 / mm 34.5 34.2 32.9 33.4 34.0 Show that the percentage uncertainty in d is about 2.4%. Assume that all the data are valid. [2 marks] 11 *11* Turn over ► IB/M/Jun22/7408/3A Do not write outside the 0 3 box . 3 The length of the cylinder is 71±2 mm. Determine the uncertainty, in mm3 , in the volume of the cylinder. [4 marks] uncertainty = mm3 Question 3 continues on the next page 12 *12* IB/M/Jun22/7408/3A Do not write outside the 0 3 box . 4 A student is given some putty to form into cylinders. To find the resistance of a cylinder, metal discs are placed in contact with the ends of the cylinder and connected to a resistance meter. Figure 7 shows the apparatus. Figure 7 The student forms the putty into cylinders of different lengths, each of volume 5.83 × 10−5 m3 . The length L and resistance R are measured for each cylinder. It can be shown that R = 2 5 5.83 10 L − × where ρ is the resistivity of the conductive putty. The student plots the graph shown in Figure 8. Determine ρ. State an appropriate SI unit for your answer. [4 marks] ρ = unit = 13 *13* Turn over ► IB/M/Jun22/7408/3A Do not write outside the Figure 8 box Turn over for the next question 11 14 *14* IB/M/Jun22/7408/3A Do not write outside the 0 4 box Figure 9 shows air trapped in a vertical cylinder by a valve and a piston P. The valve remains closed throughout the experiment. A mass is placed on top of P. P moves downwards and the volume of the trapped air decreases. There are no air leaks and there is no friction between the cylinder and P. Figure 9 The vertical distance y between the end of P and the closed end of the cylinder is measured. Additional masses are used to find out how y depends on the total mass M placed on top of P. Figure 10 shows a graph of these data. 0 4 . 1 Show that y is not inversely proportional to M. Use data points from Figure 10. [2 marks] 15 *15* Turn over ► IB/M/Jun22/7408/3A Do not write outside the Figure 10 box Question 4 continues on the next page 16 *16* IB/M/Jun22/7408/3A Do not write outside the 0 4 box . 2 The masses are removed and the cylinder is inverted. P moves downwards without friction before coming to rest, as shown in Figure 11. Figure 11 Explain why P does not fall out of the cylinder unless the valve is opened. [3 marks] 17 *17* Turn over ► IB/M/Jun22/7408/3A Do not write outside the 0 4 box . 3 The mass of P is 0.350 kg. Deduce y when the cylinder is in the inverted position shown in Figure 11. Draw a line of best fit on Figure 10 to arrive at your answer. [4 marks] y = mm Question 4 continues on the next page 18 *18* IB/M/Jun22/7408/3A Do not write outside the Figure 12 shows apparatus used in schools to investigate Boyle’s law. box Figure 12 A fixed mass of air is trapped above some coloured oil inside a glass tube, closed at the top. A pump applies pressure to the oil and the air. The trapped air is compressed and its pressure p is read from the pressure gauge. 19 *19* Turn over ► IB/M/Jun22/7408/3A Do not write outside the 0 4 . 4 A scale, marked in 0.2 cm box 3 intervals, is used to measure the volume V of the air. A student says that the reading for V shown in Figure 12 is 35.4 cm3 . State: • the error the student has made • the correct reading, in cm3 , of the volume. [2 marks] volume = cm3 Question 4 continues on the next page 20 *20* IB/M/Jun22/7408/3A Do not write outside the 0 4 box . 5 Figure 13 shows data obtained using the apparatus in Figure 12. Figure 13 Explain why the gradient of the graph in Figure 13 confirms that the air obeys Boyle’s law. [3 marks] 21 *21* IB/M/Jun22/7408/3A Do not write outside the 0 4 box . 6 The largest pressure that can be read from the pressure gauge is 3.4 × 105 Pa. Determine, using Figure 13, the volume V corresponding to this pressure. [3 marks] V = cm3 0 4 . 7 State one property of the air that must not change during the experiment. Go on to suggest how this can be achieved. [2 marks] END OF QUESTIONS 19 22 *22* IB/M/Jun22/7408/3A Do not write outside the There are no questions printed on this page box DO NOT WRITE ON THIS PAGE ANSWER IN THE SPA