Lesson 3.4.2

3.4.2 Electromotive force and internal resistance Quiz: Pearson Edexcel Physics, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.4.2, Electromotive force and internal resistance: 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. What is meant by the electromotive force (e.m.f.) of a source?

    • The charge passing through the source per second
    • The energy dissipated per unit charge in the external circuit
    • The potential difference across the terminals while the source supplies a current
    • The energy transferred per unit charge by the source from other forms into electrical energy

  2. What is meant by the internal resistance of a cell?

    • A constant resistance the cell presents to any load, regardless of the current drawn
    • Resistance of the connecting wires between the cell and the load only
    • Resistance within the cell itself, which causes energy to be lost inside the cell as charge flows through it
    • Resistance of the external circuit connected to the cell's terminals

  3. Which statement distinguishes e.m.f. from terminal potential difference?

    • E.m.f. is the energy per coulomb lost in the external circuit, while terminal p.d. is the energy supplied by the cell
    • E.m.f. is measured only when current flows, while terminal p.d. is measured when no current flows
    • E.m.f. and terminal p.d. are always equal, whatever current the source supplies
    • E.m.f. is the energy per coulomb supplied by the source, while terminal p.d. is the energy per coulomb transferred in the external circuit

  4. Which equation gives the terminal p.d. V of a cell with e.m.f. E and internal resistance r when it supplies a current I?

    • V = Ir - E
    • V = E + Ir
    • V = E/r - I
    • V = E - Ir

  5. In a graph of terminal p.d. V (y-axis) against current I (x-axis) for a cell, what do the intercept on the V-axis and the gradient represent?

    • The intercept is the e.m.f.; the magnitude of the gradient is the internal resistance
    • The intercept is the internal resistance; the gradient is the e.m.f.
    • The intercept is the terminal p.d.; the gradient is the e.m.f. divided by the internal resistance
    • The intercept is the short-circuit current; the gradient is the load resistance

  6. What are lost volts in a cell?

    • The charge lost from the cell per second
    • The e.m.f. converted to heat in the external circuit
    • The potential difference across the internal resistance, equal to Ir
    • The difference between the e.m.f. and the power supplied to a load

  7. What is the current when a cell of e.m.f. E and internal resistance r is short-circuited?

    • E r
    • E/(2r)
    • Zero
    • E/r

  8. A cell of e.m.f. 1.5 V and internal resistance 0.50 ohm supplies a current of 0.40 A. What is its terminal p.d.?

    • 1.3 V
    • 1.5 V
    • 0.20 V
    • 1.7 V

  9. A cell of e.m.f. 2.0 V and internal resistance 0.50 ohm is connected to a 2.5 ohm resistor. What current flows?

    • 0.40 A
    • 0.80 A
    • 0.67 A
    • 4.0 A

  10. Three identical cells, each of e.m.f. 1.5 V and internal resistance 0.20 ohm, are connected in series to a 4.0 ohm resistor. What current flows?

    • 1.1 A
    • 0.98 A
    • 1.5 A
    • 0.33 A

  11. Two identical cells, each of e.m.f. 1.5 V and internal resistance 1.0 ohm, are connected in parallel. What are the e.m.f. and internal resistance of the combination?

    • E = 1.5 V and r = 2.0 ohm
    • E = 3.0 V and r = 2.0 ohm
    • E = 1.5 V and r = 0.5 ohm
    • E = 3.0 V and r = 0.5 ohm

  12. A line of terminal p.d. against current has V-intercept 1.6 V and passes through the point (0.40 A, 0.80 V). What is the internal resistance?

    • 4.0 ohm
    • 1.6 ohm
    • 0.50 ohm
    • 2.0 ohm

  13. A cell has e.m.f. 6.0 V and internal resistance 0.50 ohm, and supplies a current of 4.0 A. What is its terminal p.d.?

    • 6.0 V
    • 4.0 V
    • 2.0 V
    • 8.0 V

  14. A cell of e.m.f. 2.0 V and internal resistance 0.50 ohm is connected to an external resistor of 1.5 ohm. What power is dissipated in the external resistor?

    • 0.50 W
    • 2.0 W
    • 1.0 W
    • 1.5 W

  15. A cell of e.m.f. 1.5 V transfers a total charge of 120 C round a circuit. How much energy is transferred by the cell?

    • 180 J
    • 120 J
    • 80 J
    • 1.5 J

  16. A cell of e.m.f. 3.0 V and internal resistance 1.0 ohm supplies two 4.0 ohm resistors connected in parallel. What is the terminal p.d.?

    • 1.0 V
    • 2.5 V
    • 2.0 V
    • 3.0 V

  17. A cell has e.m.f. 1.5 V and delivers a current of 1.0 A with terminal p.d. 1.0 V. What is the efficiency of the cell, as terminal p.d. divided by e.m.f.?

    • 50%
    • 100%
    • 33%
    • 67%

  18. A student finds the terminal p.d. of a cell falls as the current drawn from it increases. Which conclusion is best supported?

    • The external circuit has zero resistance at every current
    • The cell has internal resistance, so the lost volts across it increase with current
    • The e.m.f. of the cell decreases as the current increases
    • The e.m.f. of the cell increases as the external resistance is increased

  19. A cell of e.m.f. 12 V and internal resistance 2.0 ohm drives a circuit whose total external resistance is 7.0 ohm. What current flows?

    • 2.0 A
    • 0.86 A
    • 1.3 A
    • 1.7 A

  20. Why is a voltmeter reading across a cell with no load a good estimate of its e.m.f.?

    • With almost no current flowing, the lost volts Ir are negligible, so the terminal p.d. is almost equal to E
    • The internal resistance of a cell is zero when its terminals are open
    • A voltmeter has zero internal resistance, so its reading always equals the e.m.f.
    • Voltmeters measure e.m.f. directly regardless of the current flowing

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