| English | Parallel circuit |
|---|---|
| Bahasa Melayu | Litar selari |
| 中文 | 并联电路 |
Definition
A circuit in which components are connected across common points, providing more than one path for the current, with the same potential difference across each branch.
In exam terms
A parallel circuit connects components across common points, giving more than one path for the current. Its features are: the same potential difference across every branch; the total current splits among the branches and adds back up (I = I₁ + I₂ + …); and the effective resistance is found from 1/R = 1/R₁ + 1/R₂ + …, in ohms (Ω).
The effective resistance is always smaller than the smallest branch resistor.
Example of correct use: two 6 Ω resistors in parallel give 1/R = 1/6 + 1/6 = 2/6, so R = 3 Ω.
Do not confuse it with…
Do not confuse a parallel circuit with a series circuit. Here the potential difference is shared equally across branches and the current divides; in series the current is common and the potential difference divides.
A common error is adding parallel resistances directly, you must use the reciprocal formula, which gives a value lower than any single branch.
In Paper 2 you may be asked to explain why appliances at home are wired in parallel, or to calculate effective resistance and branch currents.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)