In the last blog post we learned about what magnets can do. The magnets we were using were called permanent magnets, meaning they always produce a magnetic field.
In this blog post we will learn about temporary magnets, or magnets that only sometimes produce a magnetic field. Specifically, we will learn about how to use electricity to create an electromagnet. Electromagnets are used for things like computer speakers, electric motors, and lifting trains off of their tracks so they can travel very quickly (Maglev).
What you will need:
- Large iron nail (the one I used was a 6 inch galvanized steel nail)
- About 2 metres of coated copper wire
- D cell battery
- Scissors (or wire strippers if you have them)
- Box of paperclips (or similar small metal objects)
First, have an adult strip the plastic off of the end of the wire. There should be about two centimetres of exposed metal wire. Then, start winding the wire around the nail. It is important that the wire is wrapped around the nail in one continuous direction and that the wires don't crisscross anywhere, otherwise the electromagnet won't work very well.
And... done! Have an adult strip the plastic off of the other end of the wire.
Now all that you need to do is connect each end of the wire to the different sides of the battery. If you are having a hard time holding the wires in place you can tape one side to the battery. Warning: after a bit of time the ends of the battery will start to heat up - be careful not to let it get too hot and burn yourself! Make sure when you put down the electromagnet that the wires don't stay in contact with both sides of the battery.
Now that your electromagnet is finished, test it out by trying to pick up different metal objects.
So what is happening here? When electricity moves through a wire it creates a small magnetic field. When you coil the wire up around the nail you are combining a bunch of small magnetic fields to create a larger magnetic field through the iron nail.
Test what happens when you disconnect the battery from the nail. Can the nail hold onto the paper clips?
No! This is because without electricity the magnetic field is too small to hold onto the paperclips.
Can you think of ways to make your electromagnet stronger? Some things you can change are:
- Increasing the amount of electricity travelling through the wire
- Increasing the number of loops of wire
Pretty neat, eh? Now see what else you can pick up! What happens when you try to pick up a magnet? What if you use the other side of the electromagnet? Have fun exploring!
This activity is based on the book If: Ball, Then: Catch, available here!