Lesson 3.1.2

3.1.2 Resistance, Ohm's law and I-V characteristics Quiz: Pearson Edexcel Physics, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.1.2, Resistance, Ohm's law and I-V characteristics: 20 multiple choice questions for the Pearson Edexcel Physics (9PH0), Unit 3: Electric Circuits, written with Revision Ninja.

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The 20 questions

  1. Resistance is defined by the equation:

    • R = V^2/I
    • R = I/V
    • R = V/I
    • R = VI

  2. According to Ohm's law, current is directly proportional to which quantity at constant temperature?

    • Charge flow
    • Potential difference
    • Resistance
    • Electrical power

  3. What shape is the I-V graph for an ohmic conductor at constant temperature?

    • Line through origin
    • Curved line
    • Horizontal line
    • Vertical line

  4. What happens to the resistance of a filament lamp as the current through it increases?

    • It increases
    • It becomes zero
    • It remains constant
    • It decreases

  5. The resistance of a negative temperature coefficient (NTC) thermistor as its temperature rises is:

    • Decreasing
    • Increasing
    • Constant
    • Infinite

  6. What is the resistance of a semiconductor diode connected in reverse bias?

    • Negative
    • Zero
    • Very high
    • Very low

  7. A resistor of 4.0 ohm carries a current of 2.0 A. What is the potential difference across it?

    • 2.0 V
    • 8.0 V
    • 6.0 V
    • 0.5 V

  8. A component has a potential difference of 12 V and a current of 0.30 A. What is its resistance?

    • 4.0 ohm
    • 0.025 ohm
    • 40 ohm
    • 3.6 ohm

  9. On the I-V graph of a component, the current is 0.20 A at 6.0 V. What is the resistance at this point?

    • 1.2 ohm
    • 0.033 ohm
    • 6.2 ohm
    • 30 ohm

  10. A lamp's resistance rises from 4.0 Ω to 6.0 Ω as voltage increases. What component type is it?

    • Ideal diode
    • Non-ohmic conductor
    • Superconductor
    • Ohmic conductor

  11. Why does the resistance of a metallic conductor increase as its temperature rises?

    • Increased lattice vibrations
    • Decreased ionic radius
    • Increased charge carriers
    • Decreased electron density

  12. Why does the resistance of an NTC thermistor decrease as its temperature increases?

    • More charge carriers
    • Fewer lattice vibrations
    • Decreased electron speed
    • Increased ion collisions

  13. A 10 Ω resistor has its voltage doubled from 5 V to 10 V. What is the new current?

    • 0.25 A
    • 1.0 A
    • 2.0 A
    • 0.5 A

  14. Why must temperature be kept constant when experimentally verifying Ohm's law?

    • Current would reverse
    • Voltage would drop
    • Resistance would change
    • Charge would dissipate

  15. A resistor is connected to a 9.0 V supply and carries a current of 3.0 A. What is the power dissipated in the resistor?

    • 27 W
    • 6.0 W
    • 12 W
    • 3.0 W

  16. A diode is connected in forward bias with a potential difference of 0.7 V and a current of 0.02 A. What is its resistance?

    • 0.72 ohm
    • 35 ohm
    • 0.014 ohm
    • 350 ohm

  17. An I-V graph becomes steeper as voltage increases. What happens to the component's resistance?

    • It increases
    • It becomes zero
    • It remains constant
    • It decreases

  18. A 2.5 ohm resistor and a 7.5 ohm resistor are each connected alone across the same 5.0 V supply. What is the ratio of the current in the 2.5 ohm resistor to that in the 7.5 ohm resistor?

    • 1 : 3
    • 1 : 2
    • 2 : 1
    • 3 : 1

  19. A resistor of resistance 50 ohm has a potential difference of 2.0 V across it. What current flows?

    • 25 A
    • 0.025 A
    • 0.040 A
    • 100 A

  20. Which component experiences a decrease in resistance as light intensity increases?

    • LDR
    • Filament lamp
    • Thermistor
    • Diode

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