What does the WJEC electric circuits and electromagnetism content cover?

It draws together Unit 1 topics 1.1 (electric circuits), 1.4 (domestic electricity) and 1.9 (electromagnetism). It covers current as the flow of charge, potential difference and resistance, series and parallel circuit rules, I-V characteristics, the mains supply and safety devices, electrical power and the cost of energy, magnetic fields, electromagnets, the motor effect, generators and transformers.

Which equations do I need for this content?

You should be able to select and use the charge equation (charge equals current times time), the resistance equation (potential difference equals current times resistance), the power equations (power equals potential difference times current, and power equals current squared times resistance), the energy equation (energy equals power times time), and the transformer equation (the voltage ratio equals the turns ratio). These appear on the WJEC formula list.

Which practicals appear in this content?

Investigating the I-V characteristics of a resistor, a filament lamp and a diode, and measuring current and potential difference (and resistance) in series and parallel circuits. These can be assessed in Unit 3 and sampled in the written papers.

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WJEC GCSE Physics electric circuits and electromagnetism overview

Q: How is this content examined?

It sits in Unit 1 (Electricity, Energy and Waves), a 1 hour 45 minute written paper worth 80 marks and 45% of the GCSE. Expect calculations with the charge, resistance, power and transformer equations, I-V graph interpretation, circuit reasoning, kilowatt-hour cost questions, and explanations of safety devices and the motor effect.

An overview of the electric circuits and electromagnetism content in Unit 1 of WJEC GCSE Physics (3420), mapping current, potential difference and resistance, series and parallel circuits, domestic electricity and safety, electromagnetism and the motor effect, and generators and transformers, with the key equations and how the topics are examined.

Generated by Claude Opus 4.88 min readWJEC 3420 Unit 1.1, 1.4, 1.9Updated 2026-06-14

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The content
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For the official specification

The electric circuits and electromagnetism content of WJEC GCSE Physics (specification 3420) brings together topics 1.1, 1.4 and 1.9 of Unit 1. It is about how circuits behave, how electrical energy and power are calculated, how mains electricity is supplied safely, and how currents and magnets interact to produce force and induced voltage. It is examined in Unit 1 (Electricity, Energy and Waves). This page maps the content and links to a focused answer page for each part.

The content

Current, potential difference and resistance (1.1): Current as the rate of flow of charge, the charge equation, potential difference as energy per unit charge, resistance, and $V = IR$ . See Current, potential difference and resistance.
Series and parallel circuits (1.1): Circuit symbols, the current and potential difference rules, total resistance, and the I-V characteristics of resistors, lamps and diodes. See Series and parallel circuits.
Domestic electricity and safety (1.4): The mains supply, live, neutral and earth wires, fuses, circuit breakers, earthing, the power equations, and the cost of electrical energy. See Domestic electricity and safety.
Electromagnetism and the motor effect (1.9): Magnetic fields around magnets, wires and coils, electromagnets, the motor effect and the electric motor. See Electromagnetism and the motor effect.
Generators and transformers (1.9): Electromagnetic induction, the a.c. generator, the transformer and the turns ratio. See Generators and transformers.

How this content is examined

This content sits in Unit 1, a written paper of 1 hour 45 minutes, worth 80 marks and 45% of the GCSE, tiered into Foundation and Higher. Expect calculations with the charge, resistance, power and transformer equations, I-V graph interpretation, circuit reasoning, kilowatt-hour cost questions, and explanations of safety devices, the motor effect and induction. A formula list is provided, but Higher candidates must rearrange equations.

How to study it

Know the circuit rules. Series shares the voltage with one current; parallel gives each branch the full voltage and splits the current.
Recall and apply the equations. Practise $Q = It$ , $V = IR$ , $P = VI$ , $E = Pt$ and the transformer equation until automatic.
Read I-V graphs. A straight line is ohmic; a curve (lamp) shows rising resistance; a diode conducts one way.
Learn the safety story. Earth wire plus fuse: a fault sends a surge to earth that melts the fuse.
Separate motor and generator. Left-hand rule and the motor effect give force; induction in a generator or transformer gives voltage.

For the official specification

WJEC publishes the full specification, past papers and mark schemes at wjec.co.uk. Always revise from the current specification and WJEC's own past papers, because question style, tiering and the formula list are board-specific.

Sources & how we know this

WJEC GCSE Physics specification (3420) from 2016 — WJEC (2016)