How Does an Electromagnet Work?

An electromagnet is a magnet that only works while electricity is flowing. Unlike a permanent magnet, you can switch an electromagnet on and off simply by connecting or disconnecting the battery.

In this electromagnet experiment, electricity travelled through the coil of wire wrapped around your bolt. As it flowed, it created an invisible magnetic field around the wire.

You couldn't see this invisible force—but you saw what it could do every time your junkyard crane lifted another paperclip.

Why Did the Steel Bolt Make Such a Difference?

Your first coil wrapped around the straw probably wasn't very powerful.

Then everything changed when you added the steel bolt.

Think of the steel bolt as the crane's lifting muscles. The magnetic field produced by the wire becomes much stronger when it passes through iron or steel, allowing your electromagnet to lift many more paperclips.

That's why almost every real electromagnet uses an iron or steel core.

Inside The Crazy Scientist LAB, you'll discover why iron works so well while metals like copper and aluminium don't.

Why Did More Wire Turns Lift More Paperclips?

Every loop of wire creates its own tiny magnetic field.

Imagine each loop as another teammate helping pull on the same rope. One teammate isn't very strong, but when lots of teammates pull together, the lifting force becomes much greater.

That's why adding more turns usually made your electromagnet stronger during your investigation.

Real engineers use exactly the same idea when designing powerful electromagnets for cranes, factories and electric motors.

Where Are Electromagnets Used?

The electromagnet you built today works on the same scientific idea as some amazing machines.

Engineers use electromagnets in:

• Scrap yard cranes

• Electric motors

• Loudspeakers and headphones

• Door locks

• MRI scanners

• Recycling centres

The difference isn't the science...

It's the size.

A giant scrapyard crane is simply using more electricity, more wire and a much larger steel core than the one you built at home.

Alex's Next Engineering Mission...

You've discovered two ways to make an electromagnet stronger:

•  Add a steel core.

• Add more wire turns.

But engineers are always asking the next question.

What would happen if you changed:

• the length of the bolt?

• the type of metal?

• the battery voltage?

• the thickness of the wire?

Which change do you think would make the biggest difference?

That's the next mystery waiting to be solved.