Lesson 3.13

3.13 Electronics: semiconductors, signals and operational amplifiers Quiz: AQA Physics, Unit 13

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.13, Electronics: semiconductors, signals and operational amplifiers: 20 multiple choice questions for the AQA Physics (7408), Unit 13: Electronics (A-level option), written with Revision Ninja.

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The 20 questions

  1. What voltage must gate-source voltage exceed to turn on an enhancement-mode MOSFET?

    • Pinch-off voltage
    • Threshold voltage
    • Saturation voltage
    • Breakdown voltage

  2. What feature gives a MOSFET its extremely high gate input resistance?

    • High channel doping
    • Metallic substrate
    • P-n junction bias
    • Oxide insulating layer

  3. In which operating state does a Zener diode maintain a constant reference voltage?

    • Cut-off region
    • Reverse saturation
    • Reverse breakdown
    • Forward bias

  4. How is a photodiode biased when operated in photoconductive mode?

    • Reverse biased
    • Unbiased
    • Forward biased
    • Alternating biased

  5. What physical quantity variation does a Hall effect sensor detect to measure rotational speed?

    • Electric field strength
    • Light intensity
    • Magnetic flux density
    • Acoustic pressure

  6. What determines the number of discrete quantisation levels in an analogue-to-digital converter?

    • Bandwidth limit
    • Signal amplitude
    • Bits per sample
    • Sampling frequency

  7. What minimum sampling frequency is required to accurately reconstruct a signal with maximum frequency f?

    • f
    • 2f
    • 4f
    • 0.5f

  8. How many voltage levels can an 8-bit analogue-to-digital converter represent?

    • 256
    • 128
    • 512
    • 8

  9. What is the denary value of the binary number 1010?

    • 10
    • 5
    • 12
    • 8

  10. A coil of inductance 10 mH is connected in parallel with a capacitor of capacitance 100 microfarad. What is the resonant frequency?

    • about 50 Hz
    • about 1.6 kHz
    • about 5.0 Hz
    • about 160 Hz

  11. A resonant filter has a centre frequency of 1.0 kHz and a bandwidth of 50 Hz. What is its Q factor?

    • 50
    • 1000
    • 20
    • 0.05

  12. A resonant filter with Q = 10 has a centre frequency of 500 Hz. What is its bandwidth?

    • 50 Hz
    • 500 Hz
    • 10 Hz
    • 5 Hz

  13. An ideal inverting amplifier has Rf = 10 k ohm and Rin = 1 k ohm. What is the voltage gain?

    • -10
    • +10
    • -0.1
    • -11

  14. A non-inverting amplifier has Rf = 9 k ohm and Rl = 1 k ohm. What is its voltage gain?

    • -10
    • 9
    • 10
    • 1

  15. A summing amplifier has feedback resistor Rf equal to each input resistor. Inputs are 1 V and 2 V. What is the output voltage?

    • -2.0 V
    • +3.0 V
    • -1.5 V
    • -3.0 V

  16. A difference amplifier has Rf / Rl = 5, with V+ = 2.0 V and V- = 1.5 V. What is the output?

    • 10 V
    • 2.5 V
    • 0.5 V
    • -2.5 V

  17. In an op-amp comparator, what is the output when non-inverting voltage exceeds inverting voltage?

    • Zero volts
    • Positive supply rail
    • Negative supply rail
    • Virtual earth

  18. What property of an ideal operational amplifier causes zero input current?

    • Infinite output resistance
    • Zero open-loop gain
    • Zero input resistance
    • Infinite input resistance

  19. What property forces the inverting input of an inverting op-amp to virtual earth potential?

    • High open-loop gain
    • Infinite output resistance
    • Zero input resistance
    • Low open-loop gain

  20. What happens to the open-loop gain of a real op-amp as signal frequency increases?

    • It increases
    • It decreases
    • It becomes infinite
    • It remains constant

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