how do i build an electro-magnet?

Answer 1

All you need is a battery, copper wire coated with plastic, and a metal cylinder (like a nail).

Strips the ends of the wire (expose some of the copper)

Wrap the wire around the nail numerous times (the more times the stronger the magnet).

Connect the ends of the wire to the battery.

Answer 2

Simplest example I can think off:

Pick up a roll of magnet wire at Radio Shack or electronics outlet. Get a nail and wind the wire around the length of the nail about an eighth inch thick, leaving about half inch protruding from the pointed end. Clean the two ends of the wire and attach a flash light battery to it and, as long as the battery is good and attached, you have an electro magnet.

Answer 3

The laws of magnetics say that if you run current through a coil of wire, you have an electromagnet. So, if you coil some wire up, making it look somewhat like a corkscrew, and run electricity through it, you'll have an electromagnet. Now, to make that magnet stronger, you can place some paramagnetic or ferromagnetic material inside the coils. Using the closest thing to pure iron will yield the best results. The more current you run through, the stronger the magnet. The smaller the coils, the stronger the magnet. A nail is made of steel, and they contain varying amounts of iron (Fe). If you can locate an old, 'square' nail at a garage sale or flea market, that will be almost pure iron – and will render excellent results. Old horseshoes and barrel bindings are also excellent.