Electricity Exam Questions for IGCSE Physics

This guide covers the high-mark question types in the electricity section of IGCSE Physics.

Question type 1: Ohm’s law calculations

Use V = IR to find voltage, current or resistance. Read values from a circuit diagram.

Worked example: A 12 V battery is connected to a 6 ohm resistor. Calculate the current.

I = V / R = 12 / 6 = 2 A.

Question type 2: Series and parallel circuits

For series: R_total = R1 + R2. Current is the same everywhere. Voltage is shared.

For parallel: 1/R_total = 1/R1 + 1/R2. Voltage is the same across branches. Current is shared.

Worked example: Two resistors (4 ohm and 12 ohm) are in parallel. Calculate the total resistance.

1/R = 1/4 + 1/12 = 3/12 + 1/12 = 4/12. R = 12/4 = 3 ohm.

Question type 3: Power and energy

Use P = IV, P = I^2R, E = IVt or E = Pt.

Worked example: A 3 A current flows through a 5 ohm resistor. Calculate the power dissipated.

P = I^2R = 9 x 5 = 45 W.

Question type 4: V-I characteristics

Sketch and interpret graphs for a fixed resistor (straight line through origin), filament lamp (curve) and diode (one-way). Explain why the filament lamp curve is not straight (resistance increases with temperature).

Question type 5: Transformer calculations (Extended)

Use Vp/Vs = Np/Ns and VpIp = VsIs for ideal transformers.

Practice approach

Do 10 circuit calculation questions from past papers. The marks in this section are reliable if your method is correct.