AQA A-level Physics · Topic 3.13
Practice questions covering electronics (a-level only) from this specification. Every question below is the real AQA question as it is printed on the paper, with its mark scheme.
6 questions on Electronics (A-level only), each with its mark scheme and worked method. Reveal the answer when you have had a go.
[3 marks]
Total for this question: 3
[3 marks]
Total for this question: 3
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Total for this question: 3
[3 marks]
Total for this question: 3
[3 marks]
Total for this question: 3
[3 marks]
Total for this question: 3
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Printable question pack — 3.13 Electronics (A-level only)All 180 questions across 18 specification points — 174 more than the 6 above — with the full mark scheme. Guest accessible · browser print.33 questions shown as printed, 18 reference-only · newest series first
Question and mark-scheme extracts © AQA. Reproduced for educational use; the original paper is linked on every question. Contact hello@oscarsongtutoring.co.uk for removal.
AQA 7408 · June 2025 · Paper 3BE · Q1 · 8 marks
8 marks
A timer displays 00 to 59 in 1 s steps using a 1 Hz generator, two 4-bit binary counters and two binary-to-7-segment decoders. In each counter Q0 is the least-significant output and Q3 the most-significant. A rising edge at CK advances a counter by 1, and logic 1 at active-high R resets it. The left counter counts units and receives the 1 Hz signal; the right counter counts tens. A 9 V supply represents logic 1 and 0 V logic 0. A normally open switch S is available for manual reset.
AQA 7408 · June 2025 · Paper 3BE · Q2 · 7 marks
7 marks
An ideal operational amplifier operates as a comparator on 0 V and 9 V rails to form a square-wave oscillator. Its non-inverting input V+ is at a node connected through separate 100 kohm resistors to 9 V, 0 V and Vout (positive feedback). Its inverting input is at a node connected through 33 kohm to Vout and through capacitor C to 0 V.
AQA 7408 · June 2025 · Paper 3BE · Q3 · 8 marks
8 marks
A three-stage light-intensity monitor uses operational amplifiers. Stage 1 is a reverse-biased photodiode detector/current-to-voltage converter: the op amp's non-inverting input is at 0 V; its inverting-input node X is connected to the photodiode, which is reverse biased to -12 V, and to Vout through a 10 kohm feedback resistor. The reverse photocurrent ID flows through that resistor, and X is a virtual earth. Stage 1 output drives stage 2, a non-inverting amplifier. Stage 2 output drives the non-inverting input of stage 3, a comparator on 0 V and +12 V rails. The comparator's inverting input is held at 6.8 V by a reference circuit; its output drives an LED through a series resistor to 0 V.
AQA 7408 · June 2025 · Paper 3BE · Q4 · 6 marks
6 marks
The first stage of a radio receiver connects an aerial across a parallel LC circuit whose capacitor is variable. The voltage across this tuned circuit is passed to later receiver stages.
AQA 7408 · June 2025 · Paper 3BE · Q5 · 6 marks
6 marks
A transmitter T and receiver R are beyond line of sight because of Earth's curvature. Three possible routes are considered: a ground wave following Earth's surface, a sky wave returned by the ionosphere, and a space wave relayed by a satellite.
AQA 7408 · June 2023 · Paper 3BE · Q1 · 7 marks
7 marks
A 4-bit binary counter has clock input CK, reset input R, and outputs A, B, C and D, with A the least significant bit. It is adapted as a modulo-6 counter. Outputs A, B and C then drive a logic subsystem for a seven-segment display that shows 1 to 6 in sequence. For CBA = 000, 001, 010, 011, 100 and 101, the outputs abcdefg are respectively 0110000, 1101101, 1111001, 0110011, 1011011 and 1011111.
AQA 7408 · June 2023 · Paper 3BE · Q2 · 8 marks
8 marks
Figure 4 shows a strain gauge that consists of a folded metal wire glued to a piece of insulating material. Figure 4 The resistance of the metal wire: increases when the gauge is stretched by forces applied as shown changes when there is a change in temperature.
AQA 7408 · June 2023 · Paper 3BE · Q3 · 8 marks
8 marks
A communication chain runs from an input transducer through boxes W and X to a transmitter, across a microwave link to box Y, then through an amplifier and box Z to an output transducer.
AQA 7408 · June 2023 · Paper 3BE · Q4 · 6 marks
6 marks
An operational amplifier has open-loop gain 1 x 10^5, a break frequency of 10 Hz and gain-bandwidth product 1 MHz. A separate diagram shows the usual inverting-amplifier connection: Vin passes through Rin to the inverting-input summing junction, Rf connects output to that junction, and the non-inverting input is at 0 V.
AQA 7408 · June 2023 · Paper 3BE · Q5 · 6 marks
6 marks
A noisy square-wave input drives the non-inverting input of comparator B. Zener diode A, connected to 0 V and biased from 12 V through a resistor, provides the reference at the inverting input. The comparator output drives the gate of n-channel MOSFET C through a pull-down resistor. C switches a 12 V motor, which has a reverse-biased flywheel diode across it.
AQA 7408 · June 2022 · Paper 3BE · Q5 · 6 marks
6 marks
Question 5 from AQA A-level Physics Paper 3BE, June 2022.
AQA 7408 · November 2021 · Paper 3BE · Q1 · 7 marks
7 marks
A simplified N-channel enhancement MOSFET is considered as a switch. Its output curves show saturation currents about 22, 40, 58, 75 and 94 mA for V_GS=1,2,3,4 and 5 V respectively.
AQA 7408 · November 2021 · Paper 3BE · Q2 · 7 marks
7 marks
A burglar alarm sounds only in darkness (C=1) when the door is open (A=0) or window is open (B=1). A separate circuit has two AND gates forming AC and BC, whose outputs feed a NOR gate.
AQA 7408 · November 2021 · Paper 3BE · Q3 · 8 marks
8 marks
An infrared detector uses a reverse-biased photodiode feeding the inverting input of an op-amp through a 560 kohm feedback resistor; the non-inverting input is at 0 V.
AQA 7408 · November 2021 · Paper 3BE · Q4 · 7 marks
7 marks
A Johnson decade counter gives one logic 1 sequentially at Q0-Q9. A BCD counter gives a four-bit binary-coded output. An oscilloscope pulse trace is high for 3 divisions and low for 2 divisions at 50 microseconds per division.
AQA 7408 · November 2021 · Paper 3BE · Q5 · 6 marks
6 marks
A national longwave station transmits at 0.198 MHz, amateur shortwave radio at 28.2 MHz, and a satellite television link at 10 700 MHz.
AQA 7408 · November 2020 · Paper 3BE · Q5 · 6 marks
6 marks
British embassies in Europe are to be connected by a long-distance land cable supporting simultaneous video conferences and sensitive government data. The choice is between optic fibre and copper wire.
AQA 7408 · June 2019 · Paper 3BE · Q1 · 8 marks
8 marks
Examiner report
[01.4] This item produced a good spread of marks with students tripping up at different stages of the calculation. Common mistakes were: • not appreciating that VR = 6.9 V • not using the percentage error range for the resistor • using the wrong end of the percentage tolerance range to justify the answer.
A Johnson decade counter has clock input CK and outputs Q0 to Q9. It drives a repeating traffic-light sequence red, red+amber, green, amber.
AQA 7408 · June 2019 · Paper 3BE · Q2 · 6 marks
6 marks
Examiner report
[02.2] This was a basic calculation and the equation was supplied in the Data and Formulae Booklet. Only a few students were unable to identify the input and feedback resistors with the circuit acting as a simple inverter. More students failed to gain the second mark by not transferring the negative sign in their working to the final answer line.
An op-amp circuit has input A through 100 kohm to the inverting input with 1 Mohm feedback. Input B goes through 100 kohm to the non-inverting input, which also has 1 Mohm to 0 V. Supply rails are +/-12 V.
AQA 7408 · June 2019 · Paper 3BE · Q3 · 6 marks
6 marks
Examiner report
[03.1] This was an unusual graph, but something that can be found as part of the data sheet for a probe. As such, the interpretation of the data from this type of graph is regarded as a key skill. Only the top 8% of students were able to gain all three marks. The more difficult mark was gained by those who discussed the lack of reliability in the ‘north pole facing’ arrangement across the 2.5 - 15 mm range.
A Hall sensor monitors a magnet moving towards it. With north facing, output rises steeply from about 2.0 V, peaks near 2.58 V at 4 mm, then falls toward 2.50 V. With south facing, output rises more gradually and monotonically toward 2.50 V by about 15 mm.
AQA 7408 · June 2019 · Paper 3BE · Q4 · 9 marks
9 marks
Examiner report
[04.5] Almost 80% of students were able to gain the mark for this question. Due to the way that the question was phrased, transformation alternatives were accepted. However, it should be noted that students should be encouraged only to use the functions shown in the diagram.
A 5.1 V silicon Zener diode needs at least5.0 mA to maintain its Zener voltage. In a9 V light-switch comparator, one divider branch has series resistor R from9 V to a junction and the reverse-biased Zener from that junction to0 V; the junction feeds the non-inverting input. The other branch has an LDR from9 V to a junction and a fixed resistor from that junction to0 V; this junction feeds the inverting input. LDR resistance decreases as light intensity increases.
AQA 7408 · June 2019 · Paper 3BE · Q5 · 6 marks
6 marks
Examiner report
The extended-prose item is intended to test the understanding and use of technical terms and techniques (knowledge), as well as the ability to produce clear and logical explanations. This question produced a wide spread of marks, although only 35% of students gained three marks or better. PCM is well documented in the guidance notes under ‘communications’ and is an extension of the ‘analogue and digital signals’ section which deals with ADC. Multiplexing was understood at a general level. Many students did not take the ‘Regeneration’ concept any further than to repeat the information in the question. Knowledge of the analogue modulation techniques such as PAM, PWM, PTM or PPM was not, and is not, required.
A telephone system sends 15 speech channels over one link. Analogue signals undergo PCM, the channels use TDM, and regenerators remove noise.
AQA 7408 · June 2018 · Paper 3BE · Q1 · 7 marks
7 marks
Examiner report
[01.3] This question was a little more demanding. A few students became side-tracked by expecting the manufacturer of the system also to make the logic IC’s. However, most students were able to produce a viable answer based on cost and space. 86% gained at least one mark here. Students should be shown a diagram of a typical 2-input logic gate arrangement on an IC, even if they do not use the IC.
Two logic inputs A and B feed a multi-gate circuit. The labelled intermediate outputs are C=NOT A, D=NOT B, E=C AND B and F=A AND D; the final output is Q=E OR F. A second, simpler circuit implements the same function.
AQA 7408 · June 2018 · Paper 3BE · Q2 · 7 marks
7 marks
Examiner report
[02.4] The best answers for this question came from students who appreciated that there would be a 50 kHz signal going into an operational amplifier having a gain-bandwidth product of 1 MHz, leading to a maximum gain of only 20. This approach comes from the question which asked candidates to: ‘Discuss whether this operational amplifier is suitable…’ 29% of students scored both marks. However, one mark was given if students got as far as showing that the operational amplifier really needed to have a gain-bandwidth product of twice that of the amplifier used in the circuit. The main error here was produced by students thinking that the 50 kHz signal was being transmitted by an AM system wrongly leading to a total bandwidth of 100 kHz. It will always be made clear in the question if AM/FM transmission is in use.
An ultrasound sensor must be amplified to3.0 V with voltage gain40. A non-inverting op-amp is available; detected frequency is50 kHz and gain-bandwidth product1.0 MHz.
AQA 7408 · June 2018 · Paper 3BE · Q3 · 7 marks
7 marks
Examiner report
[03.2] A large proportion of students (82%) gained this mark.
A labelled radio communication system has this sequence: input transducer -> modulator A -> amplifier B -> transmitting aerial C -> transmission path -> receiving aerial D -> amplifier E -> demodulator F -> output transducer. About55 AM stations receivable in London share540-1600 kHz.
AQA 7408 · June 2018 · Paper 3BE · Q4 · 8 marks
8 marks
Examiner report
[04.1] Most students found the calculation to be quite straight forward with very few ‘power of ten’ issues. 84% arrived at the correct answer.
A Schmitt-NOT astable has R=5.1 kohm,C=10 nF and PRF=1/(1.4RC). Another timer uses t_C=0.7(R1+R2)C and t_D=0.7R2C.
AQA 7408 · June 2018 · Paper 3BE · Q5 · 6 marks
6 marks
Examiner report
05 This question proved to be a good discriminator, with a good spread of marks. However, only a few students (18%) accessed the top mark band. There was considerable evidence of the answer evolving rather than being planned. Consequently, a number wrote a lot but said very little. In particular, only the very good students expanded on the second bullet point by considering the problems created by under- and over-sampling. 57% of students managed to score at least three marks.
A recording studio converts analogue microphone output to digital before storage.
AQA 7408 · June 2017 · Paper 3BE · Q1 · 8 marks
8 marks
Examiner report
[01.4] Unfortunately, a number of students ignored or forgot the sign in this relatively straightforward calculation. Both sign and number were needed for the single mark.
An ideal operational amplifier is first used as an inverting amplifier, then as a two-channel inverting summing amplifier. The summing amplifier has feedback resistor 150 kohm; channel 1 has 7.5 kohm and input amplitude +15 mV; channel 2 has 30 kohm and input amplitude -100 mV.
AQA 7408 · June 2017 · Paper 3BE · Q2 · 8 marks
8 marks
Examiner report
[02.3] A number of students were thrown by two aspects of this circuit which has been designed so that ‘0’ or a blank is never shown on the display. a) The counter starts at 0000, but the logic process allows the display to be ‘1’ (1 dot). Effectively the display is always one ahead of the decimal equivalent of the binary code on the counter. b) The reset binary code is 0110 and only lasts for a split second, so no output is shown for this code. However, when the reset has been completed then the counter code will be 0000 and the display will show decimal ‘1’ (1 dot). As a result of the above, students were still able to gain credit for using a single AND gate, even if they did not use the correct tap off points on the counter.
A 4-bit binary counter uses outputs A (least significant), B and C to drive seven LEDs as an electronic die. Counter states 000,001,010,011,100,101 display die faces 1-6; state 110 resets to 000.
AQA 7408 · June 2017 · Paper 3BE · Q3 · 7 marks
7 marks
Examiner report
[03.3] Some students were rather ‘clinical’ in their response to this question and forgot to relate their answer to the context of the ‘listener’.
The first-stage filter of an AM receiver is a series/parallel resonant tuning circuit with inductance 1.1 mH, adjusted to 910 kHz. Its ideal bandwidth is 10 kHz.
AQA 7408 · June 2017 · Paper 3BE · Q4 · 6 marks
6 marks
Examiner report
[04.1] This proved to be a straightforward question.
A reverse-biased photodiode and 20 kohm resistor produce voltage X for a comparator light meter. Comparator reference Y is 1.75 V. At a reverse current of 0.10 mA, the photodiode graph corresponds to about 1000 lux. The LED is connected so the comparator output sinks current when low.
AQA 7408 · June 2017 · Paper 3BE · Q5 · 6 marks
6 marks
Examiner report
This question was designed to give students the chance to write about ‘ground, sky and space waves’ related to the two radio frequency bands, LW and SW, and also to the use of microwaves as communication links. Only a relatively small number of students gained scores in the upper mark band, mainly due to confused knowledge of this part of the specification as opposed to a lack of eloquence. Use of statistics Statistics used in this report may be taken from incomplete processing data. However, this data still gives a true account on how students have performed for each question.
Longwave, shortwave and microwave links may communicate beyond the visible horizon.
AQA 7408 · sample1 · Paper 3BE · Q6 · 4 marks
4 marks
![AQA 7408 · sample1 · Paper 3BE · Q6 · 4 marks — A logic circuit has inputs A and B and output Q=(A AND B) OR [(NOT A) AND (NOT B)].](/api/paper-crops/7408/sample1/paper-3-electronics/q06/question-r1-d7abbebc.webp)
A logic circuit has inputs A and B and output Q=(A AND B) OR [(NOT A) AND (NOT B)].
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Everything here stays free. If electronics a level only is where the marks keep going, I teach it one to one from the mark schemes. Free intro call, then a free first lesson.