A-level PHYSICS Paper 3 Section B Turning points in physics

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 35. • 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 B Turning points in physics 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. 2 *02* IB/M/Jun21/7408/3BD Do not write outside the Section B box Answer all questions in this section. 0 1 Figure 1 shows the apparatus used in an experiment to investigate electron diffraction and the de Broglie hypothesis. Figure 1 0 1 . 1 Explain how high-speed electrons are produced in the apparatus in Figure 1. In your answer you should: • name parts A and B • discuss the purposes of potential differences V1 and V2. [4 marks] Do not write outside the box 3 *03* Turn over ► IB/M/Jun21/7408/3BD Do not write outside the box 0 1 . 2 In the experiment, electrons are incident on a target made of a crystalline material. The electron wavelengths need to be about 50% the size of an atom to produce a diffraction pattern on the screen. Suggest a suitable value for V2. Support your answer with a calculation. [4 marks] V2 = V Question 1 continues on the next page 4 *04* IB/M/Jun21/7408/3BD Do not write outside the 0 1 box . 3 Figure 2 shows a typical diffraction pattern produced on the screen by the electrons. Figure 2 Explain how measurements made with the apparatus in Figure 1 can be used to support the de Broglie hypothesis