Potential difference and power: past paper questions
Real questions on potential difference and power
The newest 20 of 105 written questions. Open one to see it on the real paper.
- 9702/42 · October/November 2025 · Q7a(ii)[1]
determine the root-mean-square (r.m.s.) voltage. r.m.s. voltage = V
See it on the paper → - 9702/42 · October/November 2025 · Q7b[3]
On Fig. 7.1, sketch the variation of V with t for values of t from t = 0 to t = 100 ms. 20 V / V 0 0 25 50 t / ms 75 100 – 20
See it on the paper → - 9702/21 · May/June 2025 · Q3a[1]
Define power.
See it on the paper → - 9702/21 · May/June 2025 · Q3b(i)[2]
Calculate the power transmitted to the wheels of the car by the motor. power = W
See it on the paper → - 9702/21 · May/June 2025 · Q3b(ii)[2]
Calculate the useful work done by the motor when the car travels a distance of 17 km. work done = J (ii)
See it on the paper → - 9702/22 · May/June 2025 · Q1b(iii)[3]
Between time t = 0 and time t = 5.8 s, the work done against resistive forces is 4.7 × 10 4 J. Determine the average output power of the car during this time. power = W
See it on the paper → - 9702/22 · May/June 2025 · Q1b(iv)[1]
At time t = 5.8 s, the speed of the car becomes constant. State and explain whether the output power of the car is greater than, less than or the same as the output power just before t = 5.8 s.
See it on the paper → - 9702/22 · May/June 2025 · Q6a[1]
Define electric potential difference across a component.
See it on the paper → - 9702/23 · May/June 2025 · Q3a[2]
Show that the power P developed by the engine in overcoming the total resistive force is given by the equation P = Fv .
See it on the paper → - 9702/23 · May/June 2025 · Q3b(ii)[2]
Use the information in (b)(i) to determine the power developed by the engine to move the car up the slope. power = W
See it on the paper → - 9702/23 · May/June 2025 · Q7b(ii)[2]
Calculate the e.m.f. of cell X. e.m.f. = V
See it on the paper → - 9702/23 · May/June 2025 · Q7b(iii)[2]
The cell of e.m.f. 1.2 V is replaced by a new cell with the same e.m.f. but with an internal resistance that is not negligible. State and explain the effect, if any, of the internal resistance of the new cell on the position of the null point.
See it on the paper → - 9702/52 · May/June 2025 · Q2b[2]
Values of n and the two measured values of the maximum potential difference V 1 and V 2 are given in Table 2.1. Table 2.1 2 4.30 4.20 3 3.65 3.75 4 3.30 3.20 5 2.85 2.95 6 2.65 2.55 7 2.30 2.40 V / V 1 / V –1 V V 2 / V 1 Calculate and record values of V / V and / V –1 in Table 2.1. Include the absolute uncertainties V...
See it on the paper → - 9702/52 · May/June 2025 · Q2c(i)[2]
/ V –1 against n. Include error bars for . (c) (i) Plot a graph of V V
See it on the paper → - 9702/52 · May/June 2025 · Q2c(ii)[2]
Draw the straight line of best fit and a worst acceptable straight line on your graph. Label both lines.
See it on the paper → - 9702/52 · May/June 2025 · Q2c(iii)[2]
Determine the gradient of the line of best fit. Include the absolute uncertainty in your answer. gradient = 0.44 0.42 0.40 0.38 1 –1 / V V 0.36 0.34 0.32 0.30 0.28 0.26 0.24 0.22 1 2 3 4 5 n 6 7 8
See it on the paper → - 9702/52 · May/June 2025 · Q2c(iv)[2]
Determine the y-intercept of the line of best fit. Include the absolute uncertainty in your answer. y-intercept =
See it on the paper → - 9702/22 · February/March 2025 · Q6a[2]
Calculate the potential difference between the two ends of the wire. potential difference = V
See it on the paper → - 9702/22 · October/November 2024 · Q5a[1]
Define electric potential difference (p.d.).
See it on the paper → - 9702/23 · October/November 2024 · Q6c(ii)[2]
Explain, without calculation, how the power dissipated in the wire changes as the temperature of the thermistor is increased.
See it on the paper →
What examiners said
The majority of candidates calculated the correct potential difference. Weaker candidates sometimes made a power-of-ten error when trying to convert the units of resistance from m to .
— Examiner report, February/March 2025, 9702/22 Q6(a) (Cambridge)
Different methods of calculation were possible. The most common mistake was to treat the two fixed resistors as if they were in parallel instead of in series.
— Examiner report, October/November 2023, 9702/22 Q6(b)(iii) (Cambridge)
Most candidates were able to correctly recall an appropriate formula for the power dissipated in a resistor. The most common mistake was to assume that the potential differences across the resistors were the same which then gave a final answer that was the reciprocal of the correct ratio.
— Examiner report, October/November 2023, 9702/22 Q6(b)(iv) (Cambridge)
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