Lesson 3.5.1

3.5.1 Resistance changes with temperature and illumination Quiz: Pearson Edexcel Physics, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

In partnership with Revision Ninja

Lesson 3.5.1, Resistance changes with temperature and illumination: 20 multiple choice questions for the Pearson Edexcel Physics (9PH0), Unit 3: Electric Circuits, written with Revision Ninja.

Host it live on the board and students join with a game code on their own devices, or revise alone with Free Play. The answers are revealed in the game.

Host this setFree Play

The 20 questions

  1. As the temperature of a metal conductor increases, its resistance increases. Why?

    • The ions move further apart, making it easier for electrons to flow
    • The number of conduction electrons increases, so more charge carriers are available
    • Lattice ions vibrate more, so conduction electrons collide with them more often
    • Conduction electrons travel faster and therefore collide less often

  2. The resistance of an NTC thermistor decreases as its temperature increases. Why?

    • More electrons are released into the conduction band, increasing the number of charge carriers
    • The number of conduction electrons is fixed but they move faster
    • The thermistor expands, so its cross-sectional area increases
    • Lattice vibrations increase, so electrons are scattered more strongly

  3. What happens to the resistance of an LDR when its illumination increases?

    • It stays the same, because resistance depends only on temperature
    • It increases, because photons scatter conduction electrons
    • It decreases, because more photons release more conduction electrons
    • It increases, because the length of the LDR increases

  4. Which statement describes an ohmic conductor?

    • Current is proportional to the square of the potential difference
    • Its resistance decreases as the current through it increases
    • Its resistance increases linearly with temperature at all times
    • Current is directly proportional to potential difference at constant temperature

  5. Over a typical range of temperatures, what shape does a graph of resistance against temperature have for a pure metal?

    • A horizontal line at constant resistance
    • A straight line with negative gradient through the origin
    • A curve with negative gradient
    • A straight line with positive gradient

  6. Why does the resistance of a semiconductor decrease as temperature rises, unlike a metal?

    • The number of charge carriers increases with temperature, which outweighs the increased scattering by vibrating ions
    • Its ions vibrate less at higher temperatures, so electrons collide less
    • Its conduction electrons are scattered less at higher temperature only
    • Metals have more free electrons at high temperature, which lowers their resistance

  7. What is the defining property of a negative temperature coefficient (NTC) thermistor?

    • Its resistance decreases as its temperature increases
    • Its resistance is independent of temperature
    • Its resistance decreases as it is illuminated
    • Its resistance increases as its temperature increases

  8. An NTC thermistor of resistance 3.0 kohm is in series with a fixed 1.0 kohm resistor across 8.0 V. What is the p.d. across the fixed resistor?

    • 0.67 V
    • 4.0 V
    • 6.0 V
    • 2.0 V

  9. A 1.0 kohm fixed resistor is in series with a thermistor across 8.0 V. If the thermistor resistance falls to 1.0 kohm, what is the p.d. across the fixed resistor?

    • 1.0 V
    • 4.0 V
    • 6.0 V
    • 2.0 V

  10. A metal wire has resistance 5.0 ohm at 20 C and 6.0 ohm at 80 C. Assuming a linear change, what is its resistance at 50 C?

    • 5.8 ohm
    • 6.0 ohm
    • 5.2 ohm
    • 5.5 ohm

  11. A non-ohmic component has current 0.020 A at 4.0 V and current 0.030 A at 8.0 V. What is its resistance at 8.0 V?

    • About 270 ohm
    • About 130 ohm
    • About 200 ohm
    • About 400 ohm

  12. The current-potential difference graph of a filament lamp becomes less steep at higher potential differences. Why?

    • The lamp obeys Ohm's law, so the graph should always be a straight line
    • Its resistance increases as the filament heats up, so the gradient of the I-V graph decreases
    • Its resistance decreases as it heats, so the gradient of the I-V graph increases
    • Its e.m.f. falls as the current increases

  13. An LDR in a divider with a fixed 10 kohm resistor across 5.0 V has resistance 2.0 kohm when bright. What is the p.d. across the fixed resistor?

    • 2.5 V
    • 1.0 V
    • 4.2 V
    • 0.83 V

  14. A thermistor of resistance 1.5 kohm is in series with a fixed 1.5 kohm resistor across 6.0 V. What current flows?

    • 0.50 mA
    • 4.0 mA
    • 8.0 mA
    • 2.0 mA

  15. The resistance of a metal filament rises from 10 ohm to 12 ohm as its temperature rises. What is the percentage increase?

    • 83%
    • 2%
    • 10%
    • 20%

  16. A thermistor is in series with a fixed 1.0 kohm resistor across 6.0 V, and the output is taken across the thermistor. As the temperature rises, what happens to that output?

    • It stays constant, because only the fixed resistor changes
    • It increases, because the thermistor resistance falls and takes a larger share of the supply p.d.
    • It decreases, because the thermistor resistance falls and takes a smaller share of the supply p.d.
    • It increases, because the thermistor resistance rises with temperature

  17. An NTC thermistor has resistance 5.0 kohm at 25 C and 1.0 kohm at 60 C. It is in series with a fixed 2.0 kohm resistor across 12 V. What is the p.d. across the fixed resistor at 60 C?

    • 2.0 V
    • 6.0 V
    • 8.0 V
    • 4.8 V

  18. A student says that resistance always decreases as temperature rises. Which statement best evaluates this claim?

    • It is correct, because all thermistors are ohmic
    • It is wrong for metals, whose resistance increases with temperature, so the trend depends on the material
    • It is correct, because resistance is independent of temperature for all materials
    • It is wrong, because electrons in metals are not free and temperature has no effect

  19. A point P on the I-V graph of a filament lamp has V = 6.0 V and I = 0.40 A. What is the resistance of the lamp at P?

    • 2.4 ohm
    • 15 ohm
    • 0.067 ohm
    • 6.4 ohm

  20. The resistance of an LDR does not change in simple proportion to the light intensity. Why not?

    • Light always increases the resistance of a semiconductor
    • Its resistance-illumination relationship is non-linear, so the change in resistance is not proportional to the change in intensity
    • Doubling the intensity doubles the number of photons, but not the conduction electrons
    • Its resistance depends only on the temperature of the surroundings

All Pearson Edexcel Physics quizzes