Official June 2024 AQA A-level PHYSICS 7408/2 Paper 2 Merged Question Paper + Mark Scheme + Insert Ace your Mocks!!! *JUN247408201* IB/M/Jun24/E11 7408/2 For Examiner’s Use Question Mark 1 2 3 4 5 6 7 8–32 TOTAL Thursday 6 June 2024 Morning Time allowed: 2 hours 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 85. • 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 2 2 *02* IB/M/Jun24/7408/2 Do not write outside the Section A box Answer all questions in this section. 0 1 A room contains dry air at a temperature of 20.0 °C and a pressure of 105 kPa. 0 1 . 1 Show that the amount of air in each cubic metre is about 40 mol. [1 mark] 0 1 . 2 The density of the dry air is 1.25 kg m−3 . Calculate crms for the air molecules. Give your answer to an appropriate number of significant figures. [3 marks] crms = m s−1 0 1 . 3 Calculate, in K, the change of temperature that will double crms for the air molecules. [2 marks] change of temperature = K Do not write outside the box 3 *03* Turn over ► IB/M/Jun24/7408/2 Do not write outside the 0 1 box . 4 A room contains moist air at a temperature of 20 °C. A dehumidifier cools and then condenses water vapour from the moist air. The final temperature of the liquid water that collects in the dehumidifier is 10 °C. Drier air leaves the dehumidifier at a temperature of 20 °C. Table 1 compares the air flowing into and out from the dehumidifier. Table 1 mass of water mass of air moist air flowing in 0.0057 drier air flowing out 0.0037 In one hour, a volume of 960 m3 of air flows through the dehumidifier. Assume that the density of the air remains constant at 1.25 kg m−3 . Determine how much heat energy is removed in one hour from the water vapour by the dehumidifier. specific heat capacity of water vapour = 1860 J kg−1 K−1 specific latent heat of vaporisation of water = 2.3 × 106 J kg−1 [3 marks] heat energy removed = J 9 4 *04* IB/M/Jun24/7408/2 Do not write outside the 0 2 box Figure 1 shows a circuit used to charge capacitor C. The battery has negligible internal resistance. Figure 1 The capacitance of C is known. 0 2 . 1 The switch is closed at time t = 0 and the potential difference VC across C is recorded at different times t. Figure 2 shows the variation of VC with t. Figure 2 Explain how a gradient of the graph in Figure 2 can be used to determine the initial current I0 in the circuit. [2 marks] 5 *05* Turn over ► IB/M/Jun24/7408/2 Do not write outside the 0 2 box . 2 The potential difference VR across R is also recorded. Figure 3 shows the variation of VR with t between t = 20 s and t = 45 s. Figure 3 The capacitance of C is 31.0 μF. Determine, using Figure 3, the time constant of the circuit. Go on to show that the resistance of R is about 2.4 × 105 Ω. [2 marks] time constant = s resistance = Ω Question 2 continues on the next page 6 *06* IB/M/Jun24/7408/2 Do not write outside the 0 2 box . 3 The current I0 at time t = 0 is 3.6 × 10−5 A. Determine the time at which VC is 6.0 V. [3 marks] time = s 0 2 . 4 Figure 4 shows two fully charged parallel-plate capacitors C1 and C2 in a circuit. A dielectric fills the space between the plates of C1 and air fills the space between the plates of C2. Figure 4 7 *07* Turn over ► IB/M/Jun24/7408/2 Do not write outside the Table 2 gives information about C box 1 and C2. Table 2 C1 C2 charge Q Q surface area S S potential difference V1 V2 plate separation d 2d dielectric constant 4.0 1.0 Determine 1 2 V V . [2 marks] 1 2 V V = Turn over for the next question 9 8 *08* IB/M/Jun24/7408/2 Do not write outside the 0 3 box A conducting rod is held horizontally in an east–west direction. The magnetic flux density of the Earth’s magnetic field is 4.9 × 10−5 T and is directed at an angle of 68° to the ground. 0 3 . 1 Figure 5 shows the arrangement. The rod has a length of 2.0 m. Figure 5 The rod is released and falls 8.0 m to the ground. It remains in a horizontal east–west direction as it falls. Determine the average emf across the rod during its fall to the ground. Assume that air resistance is negligible. [3 marks] average emf = V 9 *09* Turn over ► IB/M/Jun24/7408/2 Do not write outside the 0 3 box . 2 The rod is returned to its original position. It is now supported by a non-conducting pole that is hinged on the ground as shown in Figure 6. The pole is initially vertical and is then released. The rod and pole can fall to the ground to the left or to the right. Figure 6 During each fall there are changes in the magnitude and direction of the induced emf. These changes differ depending on whether the rod falls to the left or to the right. Explain any changes in the magnitude and direction of the induced emf as the rod falls: • to the left • to the right. [4 marks] left right 7 10 *10* IB/M/Jun24/7408/2 Do not write outside the 0 4 box . 1 One purpose of the coolant in a thermal nuclear reactor is to maintain a safe working temperature within the core. State the other purpose. [1 mark] 0 4 . 2 State two properties that engineers consider when choosing a liquid to use as a coolant in a thermal nuclear reactor. [2 marks] 1 2 0 4 . 3 Explain how the power output of a thermal nuclear reactor is decreased. [2 marks] 5 11 *11* Turn over ► IB/M/Jun24/7408/2 Do not write outside the Turn over for the next question box DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED 12 *12* IB/M/Jun24/7408/2 Do not write outside the 0 5 A satellite S box 1 is placed in a circular orbit around the Earth so that observations of the far side of the Moon can be made continuously. S1 has the same angular speed as the Moon so that the centres of the Earth, the Moon and S1 are always in a straight line. Figure 7 shows two positions of the Moon and S1 as they orbit the Earth. Figure 7 13 *13* Turn over ► IB/M/Jun24/7408/2 Do not write outside the 0 5 box . 1 The resultant force on S1 is due to the gravitational forces from the Earth and the Moon. The magnitude of the Earth’s gravitational field strength at the orbital radius of S1 is 1.98 × 10−3 N kg−1 . The magnitude of the Moon’s gravitational field strength at the orbital radius of S1 is gM. Show that gM is approximately 1.2 × 10−3 N kg−1 . period of the Moon’s orbit = 27.3 days orbital radius of S1 = 4.489 × 105 km [3 marks] 0 5 . 2 Calculate the distance from S1 to the centre of the Moon. mass of the Moon = 7.35 × 1022 kg [2 marks] distance = m Question 5 continues on the next page 14 *14* IB/M/Jun24/7408/2 Do not write outside the 0 5 box . 3 Another satellite S2 is placed in a circular orbit between the Earth and the Moon. S2 always views the near side of the Moon. S2 also has the same angular speed as the Moon so that the centres of the Earth, the Moon and S2 are always in a straight line. Figure 8 shows two positions of the Moon and S2 as they orbit the Earth. Figure 8 Explain how the resultant force on S2 due to the gravitational fields of the Earth and the Moon causes S2 to orbit with the same angular speed as the Moon. No calculations are required. [3 marks] 8 15 *15* Turn over ► IB/M/Jun24/7408/2 Do not write outside the 0 6 box . 1 The electric potential at a point in an electric field is −4.0 V. Explain what is meant by this statement. [3 marks] Question 6 continues on the next page 16 *16* IB/M/Jun24/7408/2 Do not write outside the box Figure 9 shows an arrangement for confining groups of electrons to small regions inside a block of gallium arsenide. Figure 9 Electrons can only move along the line PQ in the block. When a suitable electric potential is applied to the electrodes, the electrons are confined to the regions shown in Figure 9. The graph in Figure 9 shows how the electric potential V varies with distance x along PQ. 17 *17* Turn over ► IB/M/Jun24/7408/2 Do not write outside the 0 6 box . 2 Determine, using the graph in Figure 9, the maximum magnitude of the electric field. State an appropriate unit for your answer. [4 marks] maximum magnitude = unit 0 6 . 3 An electron at rest at x = 300 nm gains kinetic energy and moves to x = 800 nm. Determine the minimum kinetic energy required by the electron. [2 marks] minimum kinetic energy = J Question 6 continues on the next page 18 *18* IB/M/Jun24/7408/2 Do not write outside the 0 6 box . 4 One of the confined electrons is at x = 350 nm. Discuss the subsequent motion of this electron due to the variation in electric potential shown in Figure 9. Assume that the electron starts from rest. [3 marks] 12 19 *19* Turn over ► IB/M/Jun24/7408/2 Do not write outside the 0 7 box A team of students uses 900 dice, each with n sides, to model the decay of a radioactive material. Each dice represents a single undecayed nucleus. A throw of the dice represents a constant time interval. When the dice are thrown, those that show a 1 represent decayed nuclei and are removed. The students count the number N of ‘undecayed’ dice that remain. The procedure is repeated using the undecayed dice. Figure 10 shows the students’ data. Figure 10 0 7 . 1 Explain why N has been plotted on a logarithmic scale in Figure 10. [1 mark