Series & Parallel Circuits — A/L Physics

Series Circuit A circuit where components are connected end-to-end, forming a single path for current. The same current flows through every component. If one component fails (e.g., a bulb blows), the entire circuit breaks — like old Christmas lights. Total resistance is the sum of individual resistances.

Parallel Circuit A circuit where components are connected across the same two points, providing multiple paths for current. The voltage across each branch is the same (equal to the supply voltage). Current divides among branches. If one branch fails, current still flows through others — like household wiring, where turning off one lamp doesn't affect others.

Equivalent Resistance (Series) The single resistance that replaces a combination without changing the total current from the source. In series: R_eq = R₁ + R₂ + R₃ + … . The equivalent resistance is always larger than the largest individual resistance. Example: two 10 Ω resistors in series give 20 Ω.