Electromagnets

A magnet you can switch on and off

You probably know about magnets — those metal objects that stick to your fridge and grab paperclips. A normal magnet is always magnetic. You can never turn it off. But what if you could make a magnet that you switch on and off like a light? You can! It is called an electromagnet, and it is made using electricity.

Electromagnets are one of the most useful inventions ever. They are hiding inside doorbells, electric motors, loudspeakers and giant cranes. Let's find out how they work. (If you want to learn about ordinary magnets first, visit magnets and magnetism.)

Electricity can make magnetism

Here is the amazing secret: when electricity flows through a wire, it makes a magnetic field around the wire. A magnetic field is the invisible space where a magnet can push or pull. So a wire with electricity flowing through it becomes a little bit magnetic!

One straight wire only makes a very weak field. But if you wind the wire round and round into a coil, all the little fields add together and become much stronger. A coil of wire with electricity flowing through it is a simple electromagnet.

Making it much stronger with iron

A coil on its own is still quite weak. To make a strong electromagnet, we put a piece of iron inside the coil — usually an iron nail. This iron piece is called the core.

Iron is special because it becomes strongly magnetic when it is inside the coil's magnetic field. The iron core makes the electromagnet many times stronger. Now it can pick up a whole pile of paperclips!

So a simple electromagnet has just three parts:

• a coil of wire,
• an iron core (like a nail) inside the coil,
• a battery to push the electricity around. (The electricity flows in a loop, just like in any circuit — see how electric circuits work.)

The best part: on and off!

This is what makes electromagnets so clever. They are only magnetic while the electricity is flowing.

• Connect the battery → electricity flows → the electromagnet switches ON and grabs metal. 🧲
• Disconnect the battery → electricity stops → the electromagnet switches OFF and drops the metal.

A fridge magnet can never let go. But an electromagnet can pick something up and then drop it exactly when you want. That is incredibly handy, as we will see.

How to make an electromagnet stronger

If you want your electromagnet to pick up more, there are three easy ways to make it stronger:

1. Add more coils. The more times you wrap the wire around, the stronger the magnet. Try 20 turns, then 50 turns, and feel the difference.
2. Use a bigger battery. More electricity flowing means a stronger magnetic field. (But never go bigger than a small battery for safety.)
3. Use an iron core. As we learned, an iron nail inside the coil makes a huge difference.

Remember all three with the word more: more coils, more power, and iron inside — more magnetism!

Where we use electromagnets

Electromagnets are everywhere once you start looking:

• Scrapyard cranes use giant electromagnets to lift heavy metal and old cars. They switch on to grab the metal, swing it across, then switch off to drop it in a new pile. A normal magnet could never let go!
• Doorbells use a small electromagnet to bang a hammer against a bell when you press the button.
• Electric motors (in toys, fans and washing machines) use electromagnets to spin round and round.
• Loudspeakers and headphones use electromagnets to make sounds.
• Recycling centres use electromagnets to pull metal cans away from other rubbish so it can be sorted.

Try it yourself! 🧪

Build your own electromagnet. Ask an adult to help you gather the parts.

You need: one iron nail (about 8 cm), about 1 metre of thin coated wire, one AA or AAA battery, and a small pile of steel paperclips.

1. Leave a little wire free at one end, then wrap the rest tightly around the nail, going round and round in the same direction. The more turns, the better!
2. Carefully strip a little plastic off both ends of the wire (ask an adult).
3. Hold one bare wire end to the flat (−) end of the battery and the other bare end to the bump (+) end.
4. While the wire touches both ends, bring the nail close to the paperclips. They jump up and stick! Your electromagnet is ON.
5. Now take one wire off the battery. The paperclips fall off — the electromagnet is OFF.
6. Experiment: wrap more turns of wire and try again. Can you pick up more paperclips now?

⚠️ Safety: The wire and battery can get warm, so disconnect the battery whenever you are not testing. Use only a small battery (AA or AAA). Never use electricity from a wall socket or charger — mains electricity is very dangerous and can badly hurt you.

You have just built a magnet you can switch on and off — the same idea, made giant, that lets cranes lift cars and motors spin. Pretty powerful for a nail and some wire!