Series circuit vs Parallel circuit: what's the difference?
GCSE Physics
Two ways to connect components — as one loop, or on separate branches.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Series circuit vs Parallel circuit — side by side
| Series circuit | Parallel circuit | |
|---|---|---|
| Paths for current | One single loop | Multiple branches |
| Current | Same everywhere | Splits between branches (adds back at junctions) |
| Potential difference | Shared between components | Same across each branch |
| Adding more components | Total resistance increases | Total resistance decreases |
| If one breaks | Whole circuit stops | Other branches keep working |
Exam tip — how to tell them apart: Series: current constant, PD shares. Parallel: PD constant, current shares. That pairing is the key to most exam questions.
Common trap: Adding resistors in parallel LOWERS total resistance (more paths for current) — students often expect it to rise.
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