# 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 . 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.

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 scrapyard

## 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).