Lesson 4.3.3

4.3.3 Potential dividers Quiz: OCR Physics, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.3.3, Potential dividers: 20 multiple choice questions for the OCR Physics (H156), Unit 3: Electrons, waves and photons, written with Revision Ninja.

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The 20 questions

  1. For a potential divider of two resistors R1 and R2 in series across Vin, the output across R2 is:

    • Vout = (R1 + R2)/R2 x Vin
    • Vout = R1/(R1 + R2) x Vin
    • Vout = R2/(R1 + R2) x Vin
    • Vout = R2 x Vin/R1

  2. A potential divider has R1 = 6 ohm and R2 = 3 ohm across Vin = 9 V. What is Vout across R2?

    • 3 V
    • 9 V
    • 6 V
    • 1.5 V

  3. A potential divider with R1 = R2 = 10 k ohm is supplied with 12 V. What is Vout across R2?

    • 12 V
    • 0 V
    • 24 V
    • 6 V

  4. A thermistor is the upper resistor R1 and the output is taken across the fixed resistor R2. As temperature rises, Vout:

    • stays the same
    • becomes zero
    • decreases
    • increases

  5. Light intensity on an LDR increases. What happens to potential difference across the LDR?

    • It increases
    • It doubles
    • It decreases
    • It stays constant

  6. A potentiometer used as a potential divider is best described as:

    • a capacitor in series
    • a source of e.m.f.
    • a constant current source
    • a variable potential divider

  7. In a series circuit, the ratio V1/V2 of p.d.s across two resistors equals:

    • R1 R2
    • (R1 + R2)/R1
    • R2/R1
    • R1/R2

  8. A potential divider has R1 = 1 k ohm and R2 = 4 k ohm across Vin = 10 V. What is Vout across R2?

    • 5 V
    • 8 V
    • 2 V
    • 10 V

  9. A potential divider has R1 = 3.0 k ohm and R2 = 2.0 k ohm across Vin = 5.0 V. What is Vout across R2?

    • 5.0 V
    • 1.0 V
    • 3.0 V
    • 2.0 V

  10. A potential divider has R1 = 300 ohm and R2 = 700 ohm across Vin = 10 V. What is Vout across R2?

    • 7.0 V
    • 0.3 V
    • 10 V
    • 3.0 V

  11. In a divider with R2 and Vin fixed, decreasing R1 will:

    • leave Vout unchanged
    • decrease Vout across R2
    • increase Vout across R2
    • reduce Vin

  12. A fixed resistor R1 = 4 k ohm is connected to R2 in a potential divider. For Vout = Vin/3, what must R2 be?

    • 1 k ohm
    • 4 k ohm
    • 12 k ohm
    • 2 k ohm

  13. What property must an ideal voltmeter have to avoid changing circuit potential difference?

    • High capacitance
    • Zero resistance
    • Zero inductance
    • Infinite resistance

  14. A load resistor of 10 ohm is connected in parallel with R2 = 10 ohm in a divider with R1 = 10 ohm and Vin = 6 V. What is Vout now?

    • 3.0 V
    • 1.5 V
    • 2.0 V
    • 4.0 V

  15. A potential divider has R1 = 1 k ohm and R2 = 3 k ohm across Vin = 8 V, with a 3 k ohm load in parallel with R2. What is Vout?

    • 6.0 V
    • 2.0 V
    • 4.8 V
    • 3.2 V

  16. An LDR in the lower position has resistance 10 k ohm in dark and 1 k ohm in bright light. R1 = 2 k ohm and Vin = 6 V. What is Vout in bright light?

    • 5.0 V
    • 2.0 V
    • 3.0 V
    • 1.0 V

  17. A potential divider is designed so that Vout = Vin/2. Which condition must hold?

    • R1 = 0
    • R1 = R2
    • R1 = 2R2
    • R2 = 0

  18. A 1 k ohm resistor is placed in parallel with R2 = 1 k ohm in a divider with R1 = 1 k ohm across 6 V. What is Vout?

    • 4 V
    • 2 V
    • 3 V
    • 1.5 V

  19. A potentiometer of total resistance 10 ohm is across 4.5 V, and the slider gives 40% of the resistance. What is the output?

    • 0.45 V
    • 1.8 V
    • 4.5 V
    • 2.7 V

  20. A divider with R1 = 10 k ohm fixed and thermistor R2 = 10 k ohm at 25 C, Vin = 5 V, gives Vout = 2.5 V. If R2 falls to 5 k ohm, what is Vout?

    • 1.7 V
    • 3.3 V
    • 0.8 V
    • 2.5 V

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