Official June 2024 AQA A-level PHYSICS 7408/3A Paper 3 Section A Merged Question Paper + Mark Scheme + Insert Ace your Mocks!!! *JUN2474083A01* IB/M/Jun24/G4005/E9 7408/3A For Examiner’s Use Question Mark 1 2 3 TOTAL Monday 17 June 2024 Morning 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/Jun24/7408/3A Do not write outside the Section A box Answer all questions in this section. 0 1 This question is based on a method to determine the resistivity of a wire (required practical activity 5). Figure 1 shows a micrometer screw gauge. Figure 1 Figure 2 shows an enlarged view of the scales. Figure 2 3 *03* Turn over ► IB/M/Jun24/7408/3A Do not write outside the 0 1 box . 1 State, in mm, the resolution of the main scale. [1 mark] resolution = mm 0 1 . 2 What is the reading on the micrometer? Tick () one box. [1 mark] 6.22 mm 6.72 mm 6.78 mm 8.22 mm 0 1 . 3 A wire X is placed in the gap between the anvil and the spindle. State and explain how this gap is closed just before taking a reading of the diameter of X. [1 mark] Question 1 continues on the next page 4 *04* IB/M/Jun24/7408/3A Do not write outside the box Figure 3 shows a circuit used to determine the resistance per metre of wire X. Figure 3 Two terminals are used to mount X on a ruler. Clips are used to connect a voltmeter across the 1.2 Ω resistor. When the switch is closed, the voltmeter reading is 931 mV. The switch is then opened and the voltmeter is connected to X as shown in Figure 4. Figure 4 5 *05* Turn over ► IB/M/Jun24/7408/3A Do not write outside the 0 1 box . 4 When the switch is closed, the voltmeter reading is 397 mV. Show that, for the arrangement in Figure 4, the resistance R of the wire between the clips is about 0.5 Ω. [2 marks] Question 1 continues on the next page 6 *06* IB/M/Jun24/7408/3A Do not write outside the box The length of wire between the clips is L. Values of R are determined for different values of L. Figure 5 shows these data. Figure 5 0 1 . 5 Determine the resistance per metre of X. [2 marks] resistance per metre = Ω m−1 7 *07* Turn over ► IB/M/Jun24/7408/3A Do not write outside the 0 1 box . 6 Table 1 shows the resistance per metre of various metal wires. The diameter of X is one of the values of d shown in Table 1. Table 1 Resistance per metre of wire / Ω m−1 d / mm copper tungsten alumel nichrome 0.38 0.151 0.504 3.15 9.73 0.93 0.0247 0.0824 0.515 1.59 1.63 0.00805 0.0268 0.168 0.518 2.08 0.00494 0.0165 0.103 0.318 3.66 0.00160 0.00532 0.0333 0.103 Identify the metal used for X. Go on to determine the resistivity of the metal. State an appropriate SI unit for your answer. [4 marks] metal used for X = resistivity = SI unit = Question 1 continues on the next page 8 *08* IB/M/Jun24/7408/3A Do not write outside the 0 1 box . 7 A student adds error bars for R and L to each point on Figure 5. She estimates that • each value of R has a percentage uncertainty of 6% • each value of L has an absolute uncertainty of 5 mm. Compare her error bars for the point at L = 209 mm with her error bars for the point at L = 388 mm. [2 marks] 9 *09* Turn over ► IB/M/Jun24/7408/3A Do not write outside the 0 1 box . 8 Outline how error bars are used to determine the uncertainty in the gradient of a linear graph. [2 marks] Turn over for the next question 15 10 *10* IB/M/Jun24/7408/3A Do not write outside the 0 2 box Figure 6 shows apparatus used to investigate how the resistance R of a light-dependent resistor (LDR) varies with illumination. Figure 6 The ohm-meter • always displays a four-digit reading of R • can be set to the different ranges A to E shown in Table 2. Table 2 Setting Maximum reading displayed Minimum (non-zero) reading displayed Unit range A 199.9 000.1 Ω range B 1999 0001 Ω range C 19.99 00.01 kΩ range D 199.9 000.1 kΩ range E 1.999 0.001 MΩ 11 *11* Turn over ► IB/M/Jun24/7408/3A Do not write outside the 0 2 box . 1 Explain why the reading displayed in Figure 6 shows that the ohm-meter is set to range C. [1 mark] 0 2 . 2 The quantity EV is a measure of the intensity of the light incident on the LDR. The SI unit of EV is the lux (lx). The resistance R of the LDR is given by log(R / Ω) = −0.772 log(EV / lx) + 5.09 Show that EV for the arrangement shown in Figure 6 is about 130 lx. [2 marks] Question 2 continues on the next page 12 *12* IB/M/Jun24/7408/3A Do not write outside the R box is recorded for different values of the vertical distance x between the lamp and the LDR. EV is calculated for each value of R. Figure 7 shows how EV varies with x. Figure 7 13 *13* Turn over ► IB/M/Jun24/7408/3A Do not write outside the box It can be shown that EV 2 1 x ∝ 0 2 . 3 Describe a method to show that Figure 7 confirms this relationship. You do not need to show any calculations. [2 marks] 0 2 . 4 Deduce the value of x when EV = 130 lx. [2 marks] x = mm Question 2 continues on the next page 14 *14* IB/M/Jun24/7408/3A Do not write outside the 0 2 box . 5 R is measured when x = 450 mm. Figure 8 shows how the ohm-meter displays the values of R when set to range B and when set to range C. Figure 8 The uncertainty of the reading on the ohm-meter is ±2% of the displayed reading plus ±2 in the least significant digit. This means that: • using range B the maximum value of R is 1.02 × 1681 + 2 = 1717 Ω • using range C the minimum value of R is 0.98 × 1.68 – 0.02 = 1.63 kΩ. 15 *15* Turn over ► IB/M/Jun24/7408/3A Do not write outside the Complete Table 3 box . Go on to explain whether range B or range C should be used to measure R. [2 marks] Table 3 Setting Minimum R Maximum R range B Ω 1717 Ω range C 1.63 kΩ kΩ Question 2 continues on the next page 16 *16* IB/M/Jun24/7408/3A Do not write outside the box Figure 9 shows the LDR being used to investigate the transmission of light through glass slides. Figure 9 The lamp and ohm-meter are switched on. R is recorded with different numbers of slides placed on the LDR. EV is calculated for each value of R. 0 2 . 6 The positions of the lamp and the LDR are not changed during the experiment. Identify two other control variables. [2 marks] 1 2 17 *17* Turn over ► IB/M/Jun24/7408/3A Do not write outside the 0 2 box . 7 For the arrangement in Figure 9 it can be shown that EV = 400 e−μN where N is the number of slides μ is a constant. Explain how μ can be determined from a linear graph. [2 marks] 0 2 . 8 In an experiment μ = 9.0 × 10−2 Deduce the minimum number of slides needed to reduce EV by 50%. [2 marks] number of slides = 15 18 *18* IB/M/Jun24/7408/3A Do not write outside the 0 3 box This question is about a method to investigate how the force on a conductor varies with flux density and current (required practical activity 10). Figure 10 shows a copper rod clamped above a horizontal bench. Figure 10 19 *19* Turn over ► IB/M/Jun24/7408/3A Do not write outside the 0 3 box . 1 Describe a method to show that the copper rod is horizontal. Your method must include the use of a metre ruler. You may annotate Figure 10. [3 marks] Question 3 continues on the next page 20 *20* IB/M/Jun24/7408/3A Do not write outside the box Figure 11 shows the copper rod positioned above a digital balance. Two identical magnets are mounted on a steel yoke with their opposite poles facing each other. The balance is zeroed. The yoke is then placed on the balance so that a horizontal uniform magnetic field is applied perpendicular to the copper rod. The ends of the rod are connected as shown. Figure 11 0 3 . 2 When the switch is open, the reading on the balance shows the mass of the yoke and the two magnets. When the switch is closed, the reading on the balance decreases. Explain, with reference to Figure 11, the direction of the horizontal magnetic field. [3 marks] 21 *21* Turn over ► IB/M/Jun24/7408/3A Do not write outside the The current box I in the rod is varied. The balance reading M1 is recorded for different values of I. The switch is now opened. Two additional magnets, identical to those used before, are attached to the yoke. Figure 12 shows how this new arrangement compares with the arrangement in Figure 11. Figure 12 The balance reading with four magnets attached to the yoke is M2. With the switch open, M2 is the mass of the yoke and the four magnets. The switch is now closed. M2 is recorded for different values of I. Question 3 continues on the next page