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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
• a Data and Formulae Booklet 50 minutes on this section.
• a protractor.
For Examiner’s Use
Instructions
• 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
Do not write
outside the
Section B box
Answer all questions in this section.
0 1 Figure 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 sub-
system 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.
*02*
IB/M/Jun23/7408/3BE
, 3
Do not write
outside the
Table 1 shows how the values of CBA control the logic level applied to each of the box
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*
IB/M/Jun23/7408/3BE
, 4
Do not write
outside the
box
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 3
7
*04*
IB/M/Jun23/7408/3BE
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