is a device that becomes magnet when connected to electricity.
Unlike permanent magnets, you can easily turn on or off the
magnetic force in an electromagnet. The simplest form of an
electromagnet is a metal rod (such as an iron nail) that you
wrap some insulated wire on that.
Electromagnets are used to make
electric bells, speakers, microphones, electrical valves, electrical
door openers, electric motors, buzzers, vibrators, magnetic cranes,
televisions, magnetic storage device, tape recorders and many more.