2023 AQA A-level PHYSICS 7408/3BE Paper 3 Section B Electronics Question Paper & Mark scheme (Merged) June 2023 [VERIFIED]

2023 AQA A-level PHYSICS 7408/3BE Paper 3 Section B Electronics Question Paper & Mark scheme (Merged) June 2023 [VERIFIED] A-level PHYSICS Paper 3 Section B Electronics Thursday 15 June 2023 Morning Time allowed: The total time for Materials both sections of this paper is For this paper you must have: 2 hours. You are advised to • a pencil and a ruler spend approximately • a scientific calculator 50 minutes on this section. • a Data and Formulae Booklet • a protractor. Instructions For Examiner’s Use • Use black ink or black ball-point pen. Question Mark • Fill in the boxes at the top of this page. 1 • Answer all questions. 2 • You must answer the questions in the spaces provided. Do not write outside the box around each page or on blank pages. 3 • If you need extra space for your answer(s), use the lined pages at the end of 4 this book. Write the question number against your answer(s). 5 • Do all rough work in this book. Cross through any work you do not want to be marked. TOTAL • 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. *JUN2374083BE01* IB/M/Jun23/E9 7408/3BE 2 Section B Answer all questions in this section. 0 1Figure 1 shows the input and output pins for a 4-bit binary counter. The output pin for the least significant bit is A. Figure 1 0 1 . 1 Complete Figure 1 by adding a single logic gate to the binary counter so that the circuit functions as a modulo-6 counter. [2 marks] Figure 2 shows three outputs of the modulo-6 counter connected to a logic sub-system that controls a 7-segment display. The decimal point on the display is not shown. The whole system shown in Figure 2 is to be used as an electronic dice. Figure 2 Segments in the 7-segment display are turned on or off by the logic subsystem to display the decimal numbers 1 to 6 in sequence. A segment in the display turns on when the logic output with the same letter as the segment is at logic 1. Do not write outside the box *02* IB/M/Jun23/7408/3BE 3 Table 1 shows how the values of CBA control the logic level applied to each of the segments a to g during the counting cycle. Table 1 Logic inputs Logic outputs C B A a b c d e f g 0 0 0 0 1 1 0 0 0 0 0 0 1 1 1 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 0 1 1 0 1 1 0 0 1 1 1 0 0 1 0 1 1 0 1 1 1 0 1 1 0 1 1 1 1 1 0 1 . 2 One of the logic outputs a to g is controlled by a single NOT gate. This gate uses one of the inputs A, B or C. State the input that is used and the segment that this NOT gate controls. [1 mark] input = segment = 0 1 . 3 X represents one of the logic outputs. The Boolean expression for this output is: X= (A⋅B)+C State which of the logic outputs a to g is being controlled by this function. [1 mark] logic output = Question 1 continues on the next page Turn over ► *03* Do not write outside the box IB/M/Jun23/7408/3BE 4 0 1 . 4 Y represents another of the logic outputs. The Boolean expression for this output is: Y = (A⋅B) +(B⋅C) Complete Figure 3 to show the combination of logic gates needed to represent the expression. You should only use logic gates that represent the individual functions shown in the expression. [3 marks] Figure