7408-3A-QP-Physics-A-3Jun19-PM (1).pdf - Please write...

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* JUN1974083A01 * IB/M/Jun19/E9 7408/3A For Examiner’s Use Question Mark 1 2 3 TOTAL Monday 3 June 2019 Afternoon Materials For this paper you must have: a pencil and a ruler a scientific calculator a Data and Formulae Booklet. 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. Do all rough work in this book. Cross through any work you do not want to be marked. 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). 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 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/Jun19/7408/3A Do not write outside the box Section A Answer all questions in this section. 0 1 Figure 1 shows a sealed radioactive source used in schools and colleges. Figure 1 0 1 . 1 State two safety procedures to reduce risk when using this type of source. [2 marks] Safety procedure 1 Safety procedure 2
3 * 03 * Turn over IB/M/Jun19/7408/3A Do not write outside the box 0 1 . 2 A sealed source contains radium- 226 ( 226 88 Ra ). 226 88 Ra decays by emitting α and β particles to produce 206 82 Pb which is stable. Figure 2 is a graph of neutron number N against proton number Z , showing the different ways that 226 88 Ra can decay into 206 82 Pb . Points A to M represent all the unstable nuclei that may be formed as 226 88 Ra decays into 206 82 Pb . Figure 2 Determine the number of routes by which B can change into K . [1 mark] 0 1 . 3 Identify which of the nuclei A to M are common to all the possible ways that 226 88 Ra decays into 206 82 Pb . [3 marks] Question 1 continues on the next page
4 * 04 * IB/M/Jun19/7408/3A Do not write outside the box 0 1 . 4 The sealed source emits γ radiation in addition to α and β particles. A student uses the sealed source to investigate the inverse-square law for γ radiation. The student begins by making measurements to find the count rate A b for the background radiation. State and explain procedures to eliminate systematic error in the measurements used to find A b to reduce the percentage uncertainty in A b . [3 marks] 0 1 . 5 Figure 3 shows an aluminium absorber placed between the sealed source and a radiation detector. This is to make sure that only γ radiation from the source reaches the detector.

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