Lesson 3.5.1.2

3.5.1.2 Current-voltage characteristics Quiz: AQA Physics, Unit 5

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.5.1.2, Current-voltage characteristics: 20 multiple choice questions for the AQA Physics (7408), Unit 5: Electricity, written with Revision Ninja.

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The 20 questions

  1. According to Ohm's law, current is directly proportional to potential difference under what condition?

    • Constant physical conditions
    • Increasing temperature
    • Constant current
    • Zero resistance

  2. What is the shape of the I-V graph for an ohmic conductor?

    • Curved exponential line
    • Straight through origin
    • Vertical straight line
    • Horizontal straight line

  3. What is the approximate threshold voltage for a forward-biased silicon diode?

    • 1.5 to 2.0 V
    • 5.0 to 6.0 V
    • 0.1 to 0.2 V
    • 0.6 to 0.7 V

  4. How does the resistance of a filament lamp change as current increases?

    • It drops to zero
    • It increases
    • It decreases
    • It remains constant

  5. What is the resistance of an ideal voltmeter?

    • Variable resistance
    • Infinite resistance
    • One ohm
    • Zero resistance

  6. What is the resistance of an ideal ammeter?

    • Zero resistance
    • High resistance
    • One ohm
    • Infinite resistance

  7. On a V-I graph with voltage on the vertical axis, what does the gradient represent?

    • Charge
    • Conductance
    • Resistance
    • Resistivity

  8. Which component has a constant ratio of V to I at every point on its characteristic?

    • the filament lamp
    • the semiconductor diode
    • all three components
    • the ohmic conductor

  9. A filament lamp carries 0.20 A when the potential difference across it is 6.0 V. What power does it dissipate?

    • 30 W
    • 6.2 W
    • 1.2 W
    • 0.033 W

  10. What magnitude of current flows through a reverse-biased diode below breakdown?

    • Equal to forward
    • Infinite
    • Very high
    • Near zero

  11. A resistor has I = 0.15 A at V = 3.0 V. What is the current at V = 6.0 V if it is ohmic?

    • 0.30 A
    • 0.075 A
    • 0.45 A
    • 0.60 A

  12. A filament lamp carries 0.10 A at 2.0 V and 0.15 A at 4.0 V. What is its resistance at 4.0 V?

    • about 27 ohm
    • about 40 ohm
    • about 20 ohm
    • about 15 ohm

  13. A diode carries 20 mA at a forward voltage of 0.70 V. What is its resistance at this point?

    • 14 ohm
    • 35 ohm
    • 350 ohm
    • 0.029 ohm

  14. With voltage on the vertical axis, how does a filament lamp's V-I gradient change at higher voltage?

    • It stays constant
    • It increases
    • It drops to zero
    • It decreases

  15. Why is a filament lamp classified as a non-ohmic conductor?

    • Temperature changes resistance
    • Current is constant
    • Voltage is constant
    • Resistance is zero

  16. A lamp's resistance rises from 15 Ω to 20 Ω. By what factor does resistance increase?

    • 0.75
    • 4.00
    • 1.33
    • 2.00

  17. A 6.0 V supply is connected in series with a 100 ohm resistor and a silicon diode with 0.70 V forward voltage. What current flows?

    • 53 mA
    • 60 mA
    • 86 mA
    • 6 mA

  18. What causes the resistance of a filament lamp to increase at higher operating voltage?

    • Increased temperature
    • Decreased temperature
    • Decreased length
    • Increased area

  19. How much current flows through an ideal voltmeter connected across a circuit component?

    • One ampere
    • Infinite
    • Maximum circuit current
    • Zero

  20. A 9.0 V supply has a 200 ohm series resistor and a silicon diode with 0.65 V forward voltage. What current flows?

    • 45 mA
    • 9 mA
    • 70 mA
    • 42 mA

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