2024_AQA A-Level Physics Paper 3 Section B Turning Points in Physics (Merged Question Paper and Marking Scheme) Monday 17 June 2024

2024_AQA A-Level Physics Paper 3 Section B Turning Points in Physics (Merged Question Paper and Marking Scheme) Monday 17 June 2024 Turning points in physics Monday 17 June 2024 Materials For this paper you must have:  a pencil and a ruler  a scientific calculator  a Data and Formulae Booklet  a protractor. Instructions Morning Time allowed: The total time for both sections of this paper is 2 hours. You are advised to spend approximately 50 minutes on this section. For Examiner’s Use Question  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. Mark 1 2 3  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 35.  You are expected to use a scientific calculator where appropriate.  A Data and Formulae Booklet is provided as a loose insert. 4 TOTAL 7408/3BD IB/M/Jun24/E9 2 A-Level Physics: Paper 3 Section B – Turning Points in Physics: Exam Preview Sections Section B of Paper 3 focuses on Turning Points in Physics, which covers significant breakthroughs and experiments that have shaped our understanding of the physical world. These key moments in scientific history marked shifts in thought and paved the way for major developments in physics. 1. The Development of the Atomic Model:  Thomson’s Plum Pudding Model: Understand J.J. Thomson’s model, which suggested atoms were composed of a positively charged "pudding" with negatively charged "plums" (electrons).  Rutherford’s Gold Foil Experiment: Learn about Ernest Rutherford’s experiment, which led to the discovery of the nucleus and the development of the nuclear model of the atom. The key finding was the existence of a small, dense nucleus at the center of the atom.  Bohr Model: Study Niels Bohr’s modification of Rutherford's model, introducing quantized orbits for electrons and explaining atomic spectra. 2. The Photoelectric Effect and Quantum Theory:  Albert Einstein's Explanation: Understand Einstein’s explanation of the photoelectric effect, where light shining on a metal surface causes the emission of electrons. This experiment demonstrated that light has particle-like properties (photons), challenging the classical wave theory of light.  Wave-Particle Duality: Recognize the wave-particle duality of light and matter, which was pivotal in the development of quantum mechanics. This concept shows that particles like electrons also exhibit wave like behavior, as demonstrated in the double-slit experiment. 3. The Theory of Relativity:  Special Relativity: Learn about Einstein’s special theory of relativity, which revolutionized our understanding of space and time. Key concepts include time dilation and length contraction, as well as the famous equation E=mc2E=mc^2E=mc2, which shows the equivalence of energy and mass.  General Relativity: Study Einstein’s general theory of relativity, which explains how gravity arises from the curvature of spacetime caused by mass. This theory has been confirmed by experiments such as the bending of light around massive objects (gravitational lensing) and the observation of gravitational waves. 4. The Uncertainty Principle and Quantum Mechanics:  Heisenberg’s Uncertainty Principle: Understand the Heisenberg Uncertainty Principle, which states that the position and momentum of a particle cannot both be precisely measured at the same time. This principle is a fundamental concept in quantum mechanics.  Schrödinger’s Wave Equation: Learn about Erwin Schrödinger’s wave equation, which describes how the quantum state of a physical system changes over time. This equation is essential for understanding phenomena like electron behavior in atoms. 5. Key Concepts to Revise:  Atomic Models: Understand how the atomic model evolved from the plum pudding model to Rutherford’s nuclear model and Bohr’s quantized orbits.  Quantum Mechanics: Be familiar with key quantum concepts such as wave-particle duality, the uncertainty principle, and Schrödinger’s wave equation.  Relativity: Review Einstein’s theories of special and general relativity, and understand their implications for time, space, and gravity.  Particle Physics: Study the discovery of the electron, the Standard Model of particle physics, and the Higgs boson. IB/M/Jun24/7408/3BD 3 IB/M/Jun24/7408/3BD Do not write outside the box Section B Answer all questions in this section. Do not write outside the box 0 1 . 1 Figure 1 shows apparatus used in an experiment to measure the specific charge of the electron. Figure 1 Electrons are accelerated by the potential difference VA. The electrons then enter the region between two parallel metal plates, shown shaded in Figure 1. The parallel metal plates are separated by a distance d with a potential difference VP across them. In the same region there is a uniform magnetic field of flux density B into the plane of the diagram. Explain why the electron beam is undeflected in the shaded region shown in Figure 1. [2 marks] 4 IB/M/Jun24/7408/3BD 6 Turn over for the next question Do not write outside the box Turn over ► 0 1 . 2 Determine, using the following data, a value for the specific charge of the electron. B = 1.59 mT VP = 1.51 kV d = 5.0 cm VA = 1.00 kV [4 marks] specific charge = C kg−1 5 IB/M/Jun24/7408/3BD Do not write outside the box 0 2 . 1 Figure 2 shows a cross-sectional view of the arrangement that Millikan used to determine the charge on the electron. Figure 2 Millikan’s initial step was to determine the radius of the oil droplet. Explain how Millikan used this apparatus to determine the radius of the oil droplet. In your answer you should:  describe the procedure used, the measurements taken and any additional data required  describe how the radius was determined from the measurements  state the physical principles and assumptions involved in the determination of the radius. [6 marks] 6 IB/M/Jun24/7408/3BD Do not write outside the box Question 2 continues on the next page Turn over ► 7 IB/M/Jun24/7408/3BD Do not write outside the box 0 2 . 2 On one occasion, the radius of a droplet was determined to be 1.20 × 10−6 m. When the droplet was stationary, the voltmeter reading was 467 V. Show that the charge on the droplet was approximately 8 × 10−19 C. density of oil = 880 kg m−3 [3 marks] 8 IB/M/Jun24/7408/3BD 3 12 . Table 1 shows the percentage uncertainty in each quantity. Table 1 Quantity Percentage uncertainty radius of oil droplet 4% density of oil 1% gravitational field strength 0.1% potential difference 0.2% distance between the plates 2% Show that the absolute uncertainty in your answer to Question 02.2 is approximately ±1 × 10−19 C. Go on to discuss whether this uncertainty allows your answer to Question 02.2 to be used to support the quantisation of electric charge. Do not write outside the box [3 marks] Turn over ► 2 0 9 IB/M/Jun24/7408/3BD Do not write outside the box 0 3 Hertz did an experiment to determine the speed of radio waves. Describe this experiment. In your answer you should:  include a labelled diagram  state the measurements that were taken  describe how the data were used to determine the speed of radio waves. [5 marks] 10 IB/M/Jun24/7408/3BD Do not write outside the box Turn over for the next question Turn over ► 5 11 IB/M/Jun24/7408/3BD Do not write outside the box 0 4 Figure 3 shows a modern version of Bertozzi’s experiment to measure the kinetic energy of high-speed electrons. A timer is used to measure the time taken for a pulse of electrons to travel from the detector to the aluminium block. Figure 3 0 4 . 1 A potential difference (pd) of 1.30 MV is used to accelerate the electrons. Show that each electron gains approximately 2 × 10−13 J of kinetic energy. [1 mark] 0 4 . 2 These electrons cause the temperature of the aluminium block to increase by 68.0 K. The number of electrons that cause this increase in temperature is 4.50 × 1017 Deduce whether this increase in temperature is consistent with an accelerating pd of 1.30 MV. specific heat capacity of aluminium = 903 J kg−1 K−1 mass of aluminium block = 1.50 kg [2 marks] 12 IB/M/Jun24/7408/3BD Question 4 continues on the next page Do not write outside the box Turn over ► 0 4 . 3 The speed of the electrons between the detector and the block is 2.88 × 108 m s−1. Student A suggests that the non-relativistic equation for kinetic energy could be used. Student B suggests that the relativistic equation for kinetic energy is required in this situation. Evaluate the suggestions of student A and student B. Support your answer with calculations. [4 marks] 13 IB/M/Jun24/7408/3BD 12 END OF QUESTIONS Do not write outside the box 0 4 . 4 The timer in Figure 3 records a time of 29.8 ns. What is the proper time interval for an electron travelling from the detector to the aluminium block? Tick () one box. [1 mark] < 29.8 ns 29.8 ns > 29.8 ns 0 4 . 5 The electrons in Figure 3 were accelerated from rest in 13 stages. In each stage the electrons were accelerated by a pd of 100 kV. As a result, an electron increases its speed and kinetic energy during each stage. Compare, for an electron,  its increase in speed for the first stage with that for the last stage  its increase in kinetic energy for the first stage with that for the last stage. Justify your answer. No further calculations are required. [4 marks] 14 IB/M/Jun24/7408/3BD There are no questions printed on this page DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED Do not write outside the box 15 Additional page, if required. Write the question numbers in the left-hand margin. Question number IB/M/Jun24/7408/3BD Do not write outside the box 16 Additional page, if required. Write the question numbers in the left-hand margin. Question number IB/M/Jun24/7408/3BD Do not write outside the box 17 Additional page, if required. Write the question numbers in the left-hand margin. Question number Copyright information For confidentiality purposes, all acknowledgements of third-party copyright material are published in a separate booklet. This booklet is published after each live examination series and is available for free download from . Permission to reproduce all copyright material has been applied for. In some cases, efforts to contact copyright-holders may have been unsuccessful and AQA will be happy to rectify any omissions of acknowledgements. If you have any queries please contact the Copyright Team. Copyright © 2024 AQA and its licensors. All rights reserved. Do not write outside the box IB/M/Jun24/7408/3BD A-level PHYSICS 7408/3BD Paper 3 Section B Turning points in physics Mark scheme June 2024 Version: 1.0 Final MARK SCHEME – A-LEVEL PHYSICS – 7408/3BD – JUNE 2024 Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant questions, by a panel of subject teachers. This mark scheme includes any amendments made at the standardisation events which all associates participate in and is the scheme which was used by them in this examination. The standardisation process ensures that the mark scheme covers the students’ responses to questions and that every associate understands and applies it in the same correct way. As preparation for standardisation each associate analyses a number of students’ scripts. Alternative answers not already covered by the mark scheme are discussed and legislated for. If, after the standardisation process, associates encounter unusual answers which have not been raised they are required to refer these to the Lead Examiner. It must be stressed that a mark scheme is a working document, in many cases further developed and expanded on the basis of students’ reactions to a particular paper. Assumptions about future mark schemes on the basis of one year’s document should be avoided; whilst the guiding principles of assessment remain constant, details will change, depending on the content of a particular examination paper. No student should be disadvantaged on the basis of their gender identity and/or how they refer to the gender identity of others in their exam responses. A consistent use of ‘they/them’ as a singular and pronouns beyond ‘she/her’ or ‘he/him’ will be credited in exam responses in line with existing mark scheme criteria. Further copies of this mark scheme are available from Copyright information AQA retains the copyright on all its publications. However, registered schools/colleges for AQA are permitted to copy material from this booklet for their own internal use, with the following important exception: AQA cannot give permission to schools/colleges to photocopy any material that is acknowledged to a third party even for internal use within the centre. Copyright © 2024 AQA and its licensors. All rights reserved. 2 MARK SCHEME – A-LEVEL PHYSICS – 7408/3BD – JUNE 2024 Physics - Mark scheme instructions to examiners 1. General The mark scheme for each question shows:  the marks available for each part of the question  the total marks available for the question  the typical answer or answers which are expected  extra information to help the Examiner make his or her judgement and help to delineate what is acceptable or not worthy of credit or, in discursive answers, to give an overview of the area in which a mark or marks may be awarded. The extra information is aligned to the appropriate answer in the left-hand part of the mark scheme and should only be applied to that item in the mark scheme. At the beginning of a part of a question a reminder may be given, for example: where consequential marking needs to be considered in a calculation; or the answer may be on the diagram or at a different place on the script. In general the right-hand side of the mark scheme is there to provide those extra details which confuse the main part of the mark scheme yet may be helpful in ensuring that marking is straightforward and consistent. 2. Emboldening 2.1 In a list of acceptable answers where more than one mark is available ‘any two from’ is used, with the number of marks emboldened. Each of the following bullet points is a potential mark. 2.2 A bold and is used to indicate that both parts of the answer are required to award the mark. 2.3 Alternative answers acceptable for a mark are indicated by the use of or. Different terms in the mark scheme are shown by a / ; eg allow smooth / free movement. 3. Marking points 3.1 Marking of lists This applies to questions requiring a set number of responses, but for which candidates have provided extra responses. The general principle to be followed in such a situation is that ‘right + wrong = wrong’. Each error / contradiction negates each correct response. So, if the number of errors / contradictions equals or exceeds the number of marks available for the question, no marks can be awarded. However, responses considered to be neutral (often prefac