GCSE Physics resources
AQA GCSE Electricity
Use conservation of charge at junctions and the idea of shared potential difference. In series current is constant; in parallel the branches have the same potential difference and the total current is the sum of branch currents.
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Use conservation of charge at junctions and the idea of shared potential difference. In series current is constant; in parallel the branches have the same potential difference and the total current is the sum of branch currents.
Before you revise
Choose an answer from memory. Your result tells you what to watch for in the guide.
Core revision guide
Series and Parallel Circuits questions become manageable when the central model, evidence and exam method are kept together. Read the explanation, test the misconception and then apply the idea without looking back.
Use conservation of charge at junctions and the idea of shared potential difference. In series current is constant; in parallel the branches have the same potential difference and the total current is the sum of branch currents.
At a junction, charge cannot build up, so the current entering equals the current leaving. In one series loop every coulomb passes every component. In parallel, each branch has the same potential difference as the supply while the current divides between branches.
Resistance: V = IR (V, A, Ω). Choose each relationship from the physical change described, convert quantities into compatible units and keep the unit beside the final answer.
Misconception clinic
Read each belief, say what is wrong with it, then compare your correction.
Tempting idea: Mixing up the series and parallel rules.
Use instead: Use conservation of charge at junctions and the idea of shared potential difference. In series current is constant; in parallel the branches have the same potential difference and the total current is the sum of branch currents.
Tempting idea: Adding potential differences across parallel branches.
Use instead: At a junction, charge cannot build up, so the current entering equals the current leaving. In one series loop every coulomb passes every component. In parallel, each branch has the same potential difference as the supply while the current divides between branches.
Tempting idea: Forgetting the total current is the sum of branch currents.
Use instead: Mark the supply, junctions and component positions first, then apply one circuit rule at a time.
Retrieval practice
Worked examples
These examples expose the difference between a secure circuit rules that always help method and the common error “Mixing up the series and parallel rules.”.
Supply p.d. = 6.0 V.
Other branch current = 1.2 − 0.50 = 0.70 A.
Use parallel. Each lamp has the supply potential difference and one branch can remain complete if the other lamp is removed.
Exam precision
Do this: Mark the supply, junctions and component positions first, then apply one circuit rule at a time.
Independent practice
Write an answer before opening the marking guidance. Then edit the exact phrase or step that would gain the next mark.
Marking guidance: Award one mark for the precise statement shown in the model answer.
Model answer: Current.
Marking guidance: Award one mark for the correct relationship, one for a valid substitution and one for the final answer with its unit.
Model answer: 12 − 5 = 7 V.
Marking guidance: Award one mark for the correct relationship, one for a valid substitution and one for the final answer with its unit.
Model answer: 0.30 + 0.45 = 0.75 A.
Marking guidance: Award up to 3 marks for distinct physics points joined into a clear cause-and-effect chain.
Model answer: It measures the energy transferred per coulomb between the two points at either end of that branch.
Marking guidance: 2 marks are available for relevant, linked physics points that match the model answer.
Model answer: The loop is broken, so current stops everywhere.
Marking guidance: Award up to 3 marks for distinct physics points joined into a clear cause-and-effect chain.
Model answer: Each branch is connected across the supply, so each has the same energy transfer per coulomb as the supply.
Questions pupils ask
Use conservation of charge at junctions and the idea of shared potential difference. In series current is constant; in parallel the branches have the same potential difference and the total current is the sum of branch currents.
Mixing up the series and parallel rules. At a junction, charge cannot build up, so the current entering equals the current leaving. In one series loop every coulomb passes every component. In parallel, each branch has the same potential difference as the supply while the current divides between branches.
Useful next steps