You may be familiar with permanent magnets—the kind that hang on a refrigerator. But did you know that other magnets, called electromagnets, can be turned on and off? When turned on, electromagnets act just like permanent magnets, but if you turn them off, their magnetic properties disappear. Electromagnets are an important part of many electronic devices, like motors, loudspeakers, and hard drives. You can create an electromagnet with a simple coil of wire and a battery.