Electromagnets

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Learn about electromagnets.

This lesson includes:

  • one video
  • one activity to enhance learning.

Electromagnets

When an electric current flows in a wire, it creates a magnetic field around the wire.

This effect can be used to make an electromagnet.

A simple electromagnet comprises a length of wire turned into a coil and connected to a battery or power supply.

A simple electromagnet

You can make an electromagnet stronger by doing these things:

  • wrapping the coil around a piece of iron (such as an iron nail)
  • adding more turns to the coil
  • increasing the current flowing through the coil

There is a limit to how much current can be passed safely through the wire because the resistance of the wire causes heating.

Watch how Dr Yan makes a powerful electromagnet by wrapping copper wire around pieces of iron and attaching a small battery in this video.

Dr Yan makes a powerful electromagnet by wrapping copper wire around pieces of iron and attaching a small battery.

Electromagnets have some advantages over permanent magnets. For example:

  • they can be turned on and off
  • the strength of the magnetic field can be varied

These properties make electromagnets useful for picking up scrap iron and steel in scrapyards.

An electromagnet being used in a scrap yard.

The magnetic field of an electromagnet

The magnetic field around an electromagnet is just the same as the one around a bar magnet. It can, however, be reversed by reversing the current (turning the battery around).

Practise

Activity 1

Crossword

Solve the crossword using your electromagnet knowledge from Teachitscience

If you can't print the crossword off just use a pen and paper to write your answer to the clues.

Electromagnet Crossword

Activity 2

Quiz

Test your knowledge of electromagnets with this quiz.

There's more to learn

Have a look at these other resources around the BBC and the web.

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