Electromagnet
Electromagnet is a magnet made by running electric current through wire wrapped around a metal core.
A coil of copper wire sits wrapped around an iron nail. When a battery connects to the wire ends, electricity flows through each loop. This flow turns the nail into a magnet — the more loops, the stronger the pull. Cut the battery off, and the nail loses its pull right away.
Explaining electromagnet by grade level
When you wrap wire around a steel bar and hook it to a battery, the bar acts like a magnet. It can pick up iron filings. More wraps of wire make it stronger. Turn off the battery and the pull stops.
Projects that explore electromagnet
An electromagnet gets stronger when you increase the amount of wire wrapped around its metal core. More wraps concentrate the magnetic field produced by the electric current. In one test, a bar with 100 wraps picked up 18.15 grains of iron filings, while a bar with 50 wraps picked up only 9.9 grains.
Running electric current through wire wrapped around a nail turns it into an electromagnet that can push or pull other magnets. This magnetic force can drive motion. In a reed switch motor, each spinning magnet passes the reed switch and triggers a magnetic push from the electromagnet, keeping a cork spinning on its axle.