 A electromagnet is a iron core wrapped with a copper wire. The electric magnet pulls a steel bar which strikes a bell. Sometimes the bar hits one bell when it's pulled and another bell when it's released.  Sometimes the magnet is rapidly turned on-and-off by a switch, so you get a bell ringing repeatedly.

The loudspeakers in your radio, television or stereo system consists of a magnet surrounding an electromagnet that is attached to the loudspeaker membrane. By changing the electric current through the wires around the electromagnet, the electromagnet and the speaker can be made to go back and forth. If the variation of the electric current is at the same frequencies of sound waves, the resulting vibration of the speaker cone will create sound waves, including that from voice and music.

 A relay is a simple electromechanical switch made up of an electromagnet and a set of contacts. Relays are found hidden in all sorts of devices. In fact, some of the first computers ever built used relays to implement boolean gates.