Everything on the GCSE Physics Series & Parallel Circuits poster is written out below, section by section. Use it to search the sheet, copy parts into your own notes, or check a fact quickly.
Series circuits
In a series circuit, components are connected in a single loop end to end. Removing one component breaks the whole circuit.
- Current (I) - same everywhere: current is the same at every point. I₁ = I₂ = ...
- Voltage (V) - shared: potential difference is shared across components. V_TOTAL = V₁ + V₂ + ...
- Resistance (R) - adds: total resistance is the sum of individual resistances. R_TOTAL = R₁ + R₂. The bigger resistor takes the bigger share of potential difference.
Example: 10 V across a 2 Ω and 3 Ω resistor in series. R_TOTAL = 5 Ω. I = 10 ÷ 5 = 2 A.
Parallel circuits
In a parallel circuit, each component is on its own branch between + and -. Removing one component barely affects the others.
- Current (I) - adds: currents in each branch add to give the total. I_TOTAL = I₁ + I₂ + ...
- Voltage (V) - same on each branch: potential difference is the same across every branch. V₁ = V₂ = ...
- Resistance (R) - drops: total resistance is less than the smallest individual resistance. Adding a branch gives current another path.
Example: Two bulbs in parallel across a 6 V cell. Each bulb has the full 6 V. I_TOTAL = sum of the branch currents.
Electrical power formulas
P = V I - power (W) = potential difference (V) × current (A)
P = I² R - power (W) = current² (A²) × resistance (Ω)
E = P t - energy (J) = power (W) × time (s)
E = I V t - energy (J) = current (A) × potential difference (V) × time (s)