Edexcel International GCSE Physics Section 2: Electricity Exam Questions

About Edexcel International GCSE Physics Section 2: Electricity

Section 2 of Edexcel International GCSE Physics covers both domestic electricity and circuit theory. It begins with mains electricity, including fuses, circuit breakers, earthing and double insulation, and the heating effect of current. It then covers electrical power and energy, a.c. and d.c., series and parallel circuits, and the relationship between current, voltage and resistance, including I-V graphs for a resistor, filament lamp and diode and the behaviour of LDRs and thermistors. Charge, current and energy per unit charge complete the circuit work, and static electricity is studied as well. Examiners often ask you to choose a suitable fuse, carry out multi-step calculations and explain I-V graph shapes.

What you need to know

• Mains safety Fuses and circuit breakers break the circuit if the current is too high. The earth wire and double insulation protect users from a live casing. Choose a fuse rated slightly above the normal current.
• Power and energy Power = current x voltage (P = IV) and energy transferred = current x voltage x time (E = IVt).
• a.c. and d.c. Mains electricity is alternating current, which changes direction; cells and batteries supply direct current, which flows in one direction only.
• Resistance V = IR. In series, current is the same everywhere and voltages add up. In parallel, the voltage across each branch is the same and branch currents add to the total current.
• I-V graphs Resistor: straight line through the origin. Filament lamp: curve as resistance increases with temperature. Diode: current only flows in the forward direction. LDR resistance falls with more light; thermistor resistance falls as temperature rises.
• Charge and voltage Charge = current x time (Q = It). Voltage is the energy transferred per unit charge (V = E / Q), so 1 V = 1 J/C. Current in metals is a flow of electrons.
• Static electricity Insulators can be charged by friction as electrons are transferred. Like charges repel and unlike charges attract. Static can be dangerous (sparks near fuel) and useful (inkjet printers, photocopiers).

Common mistakes in Section 2: Electricity

• Choosing a fuse rating below the normal working current. The fuse must be just above it, otherwise it will blow in normal use.
• Saying the current gets smaller after passing through a component. Current is the same at all points in a series circuit.
• Saying an ammeter is connected in parallel. Ammeters go in series; voltmeters go in parallel.
• Describing the earth wire as carrying current all the time. It only carries current when a fault occurs.
• Saying positive charges move when objects are charged by friction. Only electrons move.

Try three Section 2: Electricity exam-style questions