What is electromagnetism? How does it work?
- Two feet of fine-gauge electrical wire
- Wire clipper
- Iron nail, about 3” long
- 9-volt battery
- Paper or ceramic plate
- Paper clips made of ferrous metal (use the small magnet to check if it’s the right kind; it should be attracted to the magnet)
- Iron filings
- Two small magnets
- Pencil and paper (or, optional, a camera)
- Use the wire cutter to strip the insulation from about one inch of each end of the wire. Be careful, this tool can snip you, too, and the ends of the wire are probably sharp!
- Wrap the wire in a snug coil around the shaft of the nail, leaving a few inches of wire dangling at each end.
- Wrap one of the dangling wire-ends around the larger connector at the top of the battery.
- Touch the other end of the wire to the other connector. Be careful! The wire might get hot now. You may want to get a partner or an adult to help you with this part.
- Now touch one end of the nail to a paper clip and see if you can move the paper clip with the nail. Has it become magnetic? Will it lift the paper clip? Will it lift two? Three? The stronger the magnetic field is, the more paper clips it will hold.
- Now, while the paper clips are sticking to the nail, move the loose end of the wire to break the connection between it and the battery. Notice how the paper clips fall. The nail hasn’t become magnetic on its own; the wire coiled around it is creating a magnetic field when the circuit is closed and electrical current runs through it.
- Want to see the magnetic field? Sprinkle a good layer of iron filings on the plate—carefully, some of them might be sharp, and you definitely don’t want to get them in your eyes!—carefully place the nail in the middle of the filings, and reconnect the wire to the battery. You should see the filings move around the nail, showing you the shape and size of the magnetic field you’re creating. Draw a picture of this (or, optionally, take a photo).
- Now take the two small magnets and place them end to end, pushing the ends together. Then flip over just one of the magnets and try it again. You should find that in one position, the ends of the magnets will stick together, and in the other position, they push each other apart. This is because magnetic fields are polar, meaning they go in one direction along a line or pole.
- Now dangle the nail from the battery and close the circuit by holding the loose wire against the second connection. See if you can make the nail move without touching it using one of the magnets. Can you flip the magnet over and make the nail move in the other direction?
Terms/Concepts: electrical field, magnetism, electromagnetism, current, circuit
References: Science Fair Adventure: Build an Electromagnet