Revision notes · Electricity
Series and parallel circuits
Series and parallel circuits4.2.2
Definition: In a series circuit, components are connected end to end in a single loop, so all the current flows through every component. In a parallel circuit, components are connected in separate branches, so the current splits between them.
| Series | Parallel | |
|---|---|---|
| Current | The same at every point in the circuit | Splits between branches — total current into a junction equals the total current out of it (current through the source = sum of currents through the branches) |
| Potential difference | Shared between components — the pd of the supply equals the sum of the pd across each component | The same across every branch — equals the pd of the supply |
| Total resistance | The sum of the resistance of each component (adding a component increases total resistance) | Less than the smallest individual resistance (adding a branch decreases total resistance, since charge has more than one path to take) |
| Switching off one component | Breaks the whole circuit — everything stops | Only that branch stops — the rest of the circuit keeps working |
🧠 Remember: Series: current same, pd shares, resistance adds up. Parallel: pd same, current shares, total resistance is smaller than the smallest branch resistance.
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