Kirchhoff’s laws: past paper questions
Real questions on kirchhoff’s laws
The newest 20 of 42 written questions. Open one to see it on the real paper.
- 9702/21 · October/November 2025 · Q5a[1]
State Kirchhoff’s first law.
See it on the paper → - 9702/22 · October/November 2025 · Q5a[1]
State Kirchhoff’s first law.
See it on the paper → - 9702/22 · October/November 2025 · Q5b(ii)[3]
Calculate the current I 2 in Y. I 2 = A
See it on the paper → - 9702/22 · October/November 2025 · Q5b(iii)[2]
Calculate the power dissipated in Y. power = W
See it on the paper → - 9702/23 · October/November 2025 · Q5a[1]
State Kirchhoff’s first law.
See it on the paper → - 9702/42 · February/March 2025 · Q5c(i)[2]
Determine the time constant τ of the circuit. Give a unit with your answer. τ = unit
See it on the paper → - 9702/42 · February/March 2025 · Q5c(ii)[2]
Determine the time taken for the discharge current to reduce to 15% of the initial discharge current. time = s
See it on the paper → - 9702/21 · May/June 2024 · Q6a[1]
State Kirchhoff’s first law.
See it on the paper → - 9702/21 · May/June 2024 · Q6b[2]
A cell with internal resistance r is connected to two resistors of resistances R 1 and R 2 as shown in Fig. 6.1. r I R 1 R 2 Fig. 6.1 The potential differences (p.d.s) across R 1 and R 2 are V 1 and V 2 respectively. The terminal p.d. across the cell is V. The current in the circuit is I . Use Kirchhoff’s laws to show...
See it on the paper → - 9702/21 · May/June 2024 · Q6d(i)[2]
the current in the cell
See it on the paper → - 9702/21 · May/June 2024 · Q6d(ii)[2]
the terminal p.d. of the cell.
See it on the paper → - 9702/22 · May/June 2024 · Q5a[1]
State Kirchhoff’s second law.
See it on the paper → - 9702/23 · May/June 2024 · Q5a(i)[1]
State Kirchhoff’s second law.
See it on the paper → - 9702/23 · May/June 2024 · Q5a(ii)[1]
State the conservation law that gives rise to Kirchhoff’s second law.
See it on the paper → - 9702/23 · May/June 2024 · Q5b(i)[2]
Use Kirchhoff’s laws to show that the total resistance R T of the external circuit is given by 1 = 1 + 1 . R T R 1 R 2
See it on the paper → - 9702/23 · May/June 2024 · Q5b(ii)[3]
The electromotive force (e.m.f.) of the cell is 1.50 V. When the values of R 1 and R 2 are 10 Ω and 15 Ω respectively, the p.d. measured by the voltmeter is 1.38 V. Calculate the internal resistance r of the cell. r = Ω
See it on the paper → - 9702/23 · May/June 2024 · Q5c(i)[2]
the current in the cell
See it on the paper → - 9702/23 · May/June 2024 · Q5c(ii)[2]
the p.d. measured by the voltmeter.
See it on the paper → - 9702/42 · February/March 2023 · Q5d[2]
A second identical resistor is now connected in parallel with R. The switch is initially in position S. When the capacitor is fully charged, the switch is moved to position T so that the capacitor discharges. At time t after the switch is moved the charge on the capacitor is Q. On Fig. 5.2, sketch a line to show the va...
See it on the paper → - 9702/23 · October/November 2022 · Q5a[2]
State Kirchhoff’s second law.
See it on the paper →
What examiners said
Most candidates knew the equation for time constant, but many then incorrectly substituted 44 μF as the capacitance of the circuit. As a result, 2.4 s was a very common incorrect answer. It was also notable that a significant number of candidates appeared to not know that time constant is a time and therefore struggled with indicating the correct unit.
— Examiner report, February/March 2025, 9702/42 Q5(c)(i) (Cambridge)
Generally well-answered by candidates that had a good understanding of the topic of capacitor discharge. Full credit by the error-carried-forward principle was common for candidates that worked through with their 2.4 s time constant from part (c)(i).
— Examiner report, February/March 2025, 9702/42 Q5(c)(ii) (Cambridge)
Most candidates realised that a straight line from the same initial value of ln Q was required, but only the strongest candidates correctly deduced the quantitative effect of the parallel resistor on the gradient of the line.
— Examiner report, February/March 2023, 9702/42 Q5(d) (Cambridge)
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