usually large scale magnets for industrial use. The magnetism is created by passing an electric current through a metal coil. This means the magnetism can be easily controlled by switching the current on or off.
An iron bar placed through the center of the coiled wire would become a temporary magnet, as long as the electric current is flowing through the wire.(Basic Science/Magnetism/electricitymagnet/discussion013.htm)(Course Material/MagParticle/Equipment/equipment1.htm)