Magnets can be great for picking stuff up, but what if you want to set stuff down again? Electromagnets can be made very strong, but also able to be turned off. You can make a simple electromagnet using materials found around the house.

First you'll need some wire, to send the electricity through. The wire needs to be insulated, meaning it needs to be coated with rubber (or some other non-metal) so that the electricity can't take short cuts through the side of the wire. You can get wire off a spool, or you can even use a wire from around your house, like the ones used for audio input/output. Longer wire works better, so try to get one that's at least 1 meter (3 feet). If you use wire off a spool, remove a bit of insulation (1 cm is enough) from both ends, so that the metal is exposed.

Next wrap the wire around the nail. Leave a few inches of wire unwrapped at the end of the wire, and start wrapping it around the nail. Depending on the length and thickness of the nail, you may have to do multiple layers of wrapping, and that's okay - just make sure you continue wrapping in the same direction (all clockwise or all counter-clockwise). Leave another few inches at the other end of the wire.

When your electromagnet is made, it's time to hook it up to the battery. Wire is designed to have very low resistance, and when you hook up both ends to the batter, the electricity races through it very quickly. This causes the wire to get quite hot. To avoid burning yourself, only keep the wire connected for short burst of time. If you want, you can tape one end of the wire (but not both!) to the battery. Touching the insulated parts of the battery helps, too. Regardless of how you do it, touch the metal ends of the wire to both ends of the battery.

Now it's time to test! With the battery hooked up, bring the tip of the nail close to a paperclip or staple. Does it work? Can it pick up two paperclips? Three? Remember to disconnect the electromagnet periodically so it doesn't get too hot.

So Why does it work?

When electricity travels in a loop, it makes a magnetic field centered down the middle of the loop. When electricity travels through more loops, the magnetic fields add, too. What do you think will happen if you use a longer wire? Or a skinny wire that lets you make more loops? Do you have to use a D-sized battery? Test out different variables and see what you can learn!