Coil Battery Magnet

Current through a coil of wire turns an iron nail into a magnet that can be switched on and off. More turns of wire or more battery current increase the magnet’s strength.

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Age 13: open this week

In the picture

Few copper turns around the left iron nail
One battery wired to the left coil
Dense copper turns around the right iron nail
Three stacked batteries wired to the right coil
Bare iron nail with two tacks beside it and no wire connected

Examples

Doorbells use an electromagnet to hit a chime.
Scrapyard cranes use electromagnets to lift and drop metal.

Key takeaways

An electromagnet is magnetic only while current flows.
More coil turns or more current make it stronger.

Carry on in the app

Three questions on this lesson. It has left the free week, so its quiz is for subscribers.

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