AQA GCSE Parallel Circuits(Physics)

YouTube video

This video is hosted by YouTube (Google). Allow Optional functionality in Cookie settings to load it. YouTube may then store or access information on your device and receive information about your visit.

Parallel Circuits

A parallel circuit contains electrical components that are in a branched circuit. 

Parallel circuit with two bulbs

Rules for Parallel Circuit diagram

Rule 1: The potential difference is the same across each component in a parallel circuit

Parallel circuit diagram with 2 bulbs in parallel, showing potential difference is the same across all components

 In the circuit above, the potential difference is the same across all components

Rule 2: In a parallel circuit, total current through the whole circuit is the sum of the currents through the separate components.

Parallel circuit showing how the current splits at a junction and then rejoins

This means that at a junction, the current splits. Think of this  just like the water flow splits in a pipe at a junction. 

Rule 3: The total resistance in a parallel circuit is less than the value of resistance for the lowest single resistor.

Parallel circuit with two resistors a 2 ohm and a 4 ohm

 In the circuit diagram above the total resistance will be lower than the resistor with the least value. In this case, total resistance is < 2 ohms.

You do not need to know how to calculate the exact value on AQA.

You do need to know that as more resistors are added in parallel, total resistance decreases because this is adding more branches to the circuit, so there are more routes for the current to flow.

Practice Questions

1.In the circuit below calculate the value for the potential difference across both the cell and one of the bulbs. 

Calculation of potential difference in a parallel circuit

 2. Calculate the missing value for current for the ammeters in the circuit below. Assume that  all bulbs are identical.

Calculating current in a parallel circuit

3. A parallel circuit contains 3 resistors, wired in parallel 10 ohm, 5 ohm and 4 ohm resistor. State the value for the total resistance of the circuit.

Cookie preferences

Optional categories start off. You can change your choice at any time using Cookie settings.

Withdrawing consent reloads this page to stop previously loaded optional scripts. Unsaved form entries may be lost.

Cookie purposes and service details