# Parallel circuits

Components on separate branches. The voltage across each branch is the same as the supply. The current splits between branches and rejoins. Adding branches lowers the total resistance.

Physics (school) · Part 06: Electric circuits · Card 6 of 8 · Last updated 2026-10-19

## Analogy

A river that splits into streams, then joins up again.

## Example

**Two branches**

Supply = 6 V.
Branch A: 2 ohms, I = 6 / 2 = 3 A
Branch B: 3 ohms, I = 6 / 3 = 2 A
Total current = 3 + 2 = 5 A

## In practice

House lights are in parallel, so each works on its own and gets the full mains voltage.

## Practice

### Flashcards

- **In a parallel circuit, what is the same across every branch?** The potential difference.

### Interview questions

**Compare series and parallel circuits for lights in a house.**

- Series: one break stops all components, voltage shared
- Parallel: each branch has full voltage and works independently
- Houses use parallel so each light can be switched separately

## Questions people ask

### Why does adding a branch in parallel lower total resistance?

A new branch gives the current another route to take. With more routes, more charge can flow for the same voltage, so the total current rises. Since resistance equals voltage divided by current, a bigger current means a smaller total resistance, even though each branch has its own resistance.

### Why are household appliances wired in parallel?

Each appliance gets the full supply voltage and can be switched on or off independently. If one fails, the others keep working. In a series arrangement, each would receive only a share of the voltage, and a single break would stop everything.

## Related concepts

- [Series circuits](https://studyvisually.com/learn/science/physics-school/physics-school-part-6/physics-school-part-6-concept-5)
- [Ohm's law](https://studyvisually.com/learn/science/physics-school/physics-school-part-6/physics-school-part-6-concept-4)
- [Circuit symbols and components](https://studyvisually.com/learn/science/physics-school/physics-school-part-6/physics-school-part-6-concept-8)

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