# Motor effect

A wire carrying current in a magnetic field feels a force. Reversing the current or the field reverses the force. A coil between two magnets will spin, which is how an electric motor works.

Physics (school) · Part 07: Mains electricity and magnetism · Card 7 of 8 · Last updated 2026-10-19

## Analogy

The wire is pushed sideways, like a hand shoving a door.

## In practice

Electric motors in fans, washing machines and electric cars use this effect.

## Practice

### Flashcards

- **What is the motor effect?** A current-carrying wire in a magnetic field feels a force.

### Interview questions

**Explain how an electric motor works.**

- A current-carrying coil sits in a magnetic field
- Each side of the coil feels an opposite force
- The coil rotates
- A split-ring commutator reverses the current every half turn

## Questions people ask

### How can the force on a wire in a magnetic field be made bigger?

Increase the current, use a stronger magnet, or use a longer length of wire inside the field. The force is greatest when the wire is at right angles to the field and zero when it is parallel. Fleming's left-hand rule helps predict the direction.

### How does an electric motor keep spinning?

A coil of wire sits between two magnets. Current gives one side an upward force and the other a downward force, so the coil turns. A split-ring commutator reverses the current every half turn, so forces always push the coil round in the same direction.

## Related concepts

- [Magnetic fields](https://studyvisually.com/learn/science/physics-school/physics-school-part-7/physics-school-part-7-concept-5)
- [Electromagnetic induction](https://studyvisually.com/learn/science/physics-school/physics-school-part-7/physics-school-part-7-concept-8)
- [Static electricity](https://studyvisually.com/learn/science/physics-school/physics-school-part-7/physics-school-part-7-concept-1)
- [Mains electricity](https://studyvisually.com/learn/science/physics-school/physics-school-part-7/physics-school-part-7-concept-2)

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