# Electromagnetic induction

A voltage is induced in a wire when it moves through a magnetic field, or when the field around it changes. This is how generators make electricity.

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

## Analogy

Like rubbing two things together to make a spark, but with a magnet and a coil.

## Example

**Ways to increase it**

Move the magnet faster.
Use a stronger magnet.
Use more turns in the coil.
Stopping the magnet gives zero.

## In practice

A bicycle dynamo and power-station generators spin magnets inside coils to make a.c.

## Practice

### Flashcards

- **What is electromagnetic induction?** Making a voltage by moving a wire through a magnetic field.

## Questions people ask

### How does a generator make electricity?

A coil spins in a magnetic field, or a magnet spins inside a coil. The wire cuts through the field, which induces a voltage across the ends of the coil. Because the coil keeps turning, the voltage keeps changing direction, so a simple generator produces alternating current.

### How could you make a larger induced voltage?

Move the magnet or coil faster, use a stronger magnet, or add more turns to the coil. Each change makes the magnetic field through the coil change more quickly. If nothing moves, the field through the coil does not change, so no voltage is induced.

## Related concepts

- [Motor effect](https://studyvisually.com/learn/science/physics-school/physics-school-part-7/physics-school-part-7-concept-7)
- [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)
- [Magnetic fields](https://studyvisually.com/learn/science/physics-school/physics-school-part-7/physics-school-part-7-concept-5)

Web page: https://studyvisually.com/learn/science/physics-school/physics-school-part-7/physics-school-part-7-concept-8
Study this card in the app: https://studyvisually.com/app/learn?category=physics-school&card=physics-school-part-7-concept-8