O Level Combined Science 5129 · Topic 26

Electricity: past paper questions

207 real questionsasked in 10 of the last 10 exam series2019–2025usually: Calculate, Explain, State, Describe, Suggest

Real questions on electricity

The newest 20 of 138 written questions, plus 69 multiple-choice. Open one to see it on the real paper.

5129/21 · October/November 2025 · Q15a[2]
When the teacher touches the dome with the wooden stick, the current I in the stick is initially 7.2 × 10 –7 A. Assume that these values of Q and I stay constant. Calculate the time to discharge the dome. time = s (a) The charge Q on the dome is initially 1.6 × 10 –6 C.
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5129/21 · October/November 2025 · Q15b(i)[1]
Suggest one electrical property of the wooden stick that is constant.
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5129/21 · October/November 2025 · Q15b(ii)[1]
In reality, the potential difference of the charged dome decreases as it discharges. This means that the actual time taken to discharge the dome is more than the time calculated in (a). Explain why the decreasing potential difference causes the time to discharge the dome to increase.
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5129/22 · October/November 2025 · Q2b(ii)[2]
Describe the electrical conductivity of oxygen and of potassium oxide. oxygen potassium oxide
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5129/22 · October/November 2025 · Q2b(iii)[2]
Potassium melts at 63.5 °C and boils at 759 °C. Place a tick (3) in the box next to the state of potassium at 810 °C. Explain your choice. liquid solid gas explanation
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5129/22 · October/November 2025 · Q3a[1]
Calculate the weight of the toy rocket. Gravitational field strength g = 10 N / kg. weight = N
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5129/22 · October/November 2025 · Q3b(i)[1]
State the acceleration of free fall. acceleration of free fall = m / s 2 (i)
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5129/22 · October/November 2025 · Q3b(ii)[2]
State the names of the two forces that act on the rocket as it falls. and
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5129/22 · October/November 2025 · Q3b(iii)[1]
The force acting to slow the rocket is negligible at low speeds. Calculate the speed of the rocket when it has fallen for 2 seconds from rest. speed = m / s
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5129/22 · October/November 2025 · Q12a(i)[1]
P = W Calculate the input power P to the motor. (i)
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5129/22 · October/November 2025 · Q12a(ii)[1]
Show that the potential difference across the 10 Ω resistor is 1.2 V.
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5129/22 · October/November 2025 · Q12a(iii)[3]
Show that the resistance in the motor and the resistance of the resistor have a combined total resistance of approximately 38 Ω.
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5129/22 · October/November 2025 · Q12b[1]
An electric current that is too large will damage the motor. State the name of a component that switches off the current in the circuit when it becomes too large.
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5129/22 · May/June 2025 · Q9b(iii)[3]
The battery supplies a voltage of 20 V. Calculate the current in the drill. current = A
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5129/32 · May/June 2025 · Q3a(i)[1]
Draw a circuit diagram of the arrangement of voltmeter and solar cell that the student uses. Include a switch to turn the voltmeter reading on and off. (i)
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5129/32 · May/June 2025 · Q3a(ii)[1]
Fig. 3.2 shows the reading on the voltmeter when the switch is closed. .8 0 0 2. 2 0. 1.0 1.2 1 .4 1 .6 0.8 0 .6 0.4 1 Fig. 3.2 Record the voltage. voltage = V (ii)
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5129/32 · May/June 2025 · Q3a(iii)[1]
One source of experimental inaccuracy in reading the scale of the voltmeter is parallax (line-of-sight) error. Tick the box that describes parallax error.
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5129/32 · May/June 2025 · Q3a(iv)[1]
Describe one other possible source of inaccuracy in the measurement of the voltage.
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5129/32 · May/June 2025 · Q3b(i)[1]
Predict the relationship between the two variables that will be shown by this investigation.
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5129/32 · May/June 2025 · Q3b(ii)[4]
Prepare a results table for this investigation. In your table include: • • • a suitable range and number of measurements for the independent variable a suitable number of columns or rows to allow repeat measurements for the dependent variable to ensure the accuracy of the results suitable units for each variable in the...
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What examiners said

Many candidates were unable to distinguish between the two resistors that were in series and the single resistor that was in parallel with them. In consequence, they incorrectly added all of the resistances together.
— Examiner report, October/November 2023, 5129/21 Q13(a) (Cambridge)

Only the most able candidates recalled that in this circuit the current in the ammeter is the sum of the current in the two branches. In this situation candidates needed to deduct 0.045 A from 0.11 A.
— Examiner report, October/November 2023, 5129/21 Q13(b) (Cambridge)

Most candidates knew that symbol B was a lamp. Many candidates stated that symbol A was a resistor, but this is not precise enough. It is a variable resistor.
— Examiner report, October/November 2023, 5129/21 Q13(c)(i) (Cambridge)

Practise this topic

Answer these questions online and get each one marked against the official mark scheme, with what you missed and how to fix it.

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In the syllabus

26.1 Electrical quantities

State that there are positive and negative charges and that charge is measured in coulombs
State that unlike charges attract and like charges repel
Describe and be able to do experiments to show electrostatic charging by friction
Explain that the charging of solids by friction involves only a transfer of negative charge (electrons)
State examples of electrical conductors and insulators
Describe examples where electrostatic charge is a problem, including lightning and aircraft refuelling
Describe examples where electrostatic charge is helpful, including photocopiers, insecticide sprayers and spray painting Define electric current as charge passing a point per unit time; recall and use the equation charge electric current = time Q I= t Describe electrical conduction in metals in terms of the movement of free (delocalised) electrons Describe the use of and be able to use ammeters (analogue and digital) with different ranges

26.1 Electrical quantities continued

Describe the use of and be able to use voltmeters (analogue and digital) with different ranges
Calculate the total voltage available from several sources arranged in series Recall and use the equation p.d. resistance = current V R= I Describe and be able to do an experiment to determine resistance using a voltmeter and an ammeter and do the appropriate calculations
Calculate the combined resistance of two or more resistors in series

26.2 Electrical circuits

Draw and interpret circuit diagrams with cells, batteries, power supplies, switches, resistors (fixed and variable), heaters, thermistors (NTC only), light-dependent resistors (LDRs), lamps, motors, ammeters, voltmeters, coils, fuses, diodes and light-emitting diodes (LEDS) Recall and use in calculations, the fact that: (a) the current at every point in a series circuit is the same (b) the sum of the currents entering a junction in a parallel circuit is equal to the sum of the currents that leave the junction (c) the total p.d. across the components in a series circuit is equal to the sum of the individual p.d.s across each component (d) the p.d. across an arrangement of parallel resistances is the same as the p.d. across one branch in the arrangement of the parallel resistances

26.3 Practical electricity

State common uses of electricity, including heating, lighting, battery charging and powering motors and electronic systems
Recall and use the equation power = current × voltage P = IV
Recall and use the equation energy = current × voltage × time E = IVt
Define the kilowatt-hour (kW h) and calculate the cost of using electrical appliances where the energy unit is the kW h State the hazards of: (a) damaged insulation (b) overheating cables (c) damp conditions (d) excess current from overloading of plugs, extension leads, single and multiple sockets when using a mains supply Explain the use and operation of trip switches and fuses and choose appropriate fuse ratings and trip switch settings Explain what happens when a live wire touches a metal case that is earthed Explain why the outer casing of an electrical appliance must be either non-conducting (double insulated) or earthed
Know that a mains circuit consists of a live wire (line wire), a neutral wire and an earth wire and explain why a switch must be connected in to the live wire for the circuit to be switched off safely
Explain why fuses and circuit breakers are connected into the live wire

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