Electromagnetism is formed by the application of electric current to a special type of magnet that only produces a magnetic field when power is applied. Electromagnets are common in everyday items and objects, with a speaker being just one example.
Any electromagnet is essentially composed of a conductive metal surrounded by wire, and the electromagnetic crane is no exception. An iron core is surrounded by wire that serves as the medium for the electricity.
The power of an electromagnet is determined by a number of factors, including the size of the iron core, the amount of times the wire is looped around the core itself and the amount of current that is passing through the wire. In the case of an electromagnetic crane, the power required is significant if it is to be able to lift large amounts of heavy metal, which accounts for the large size of an electromagnetic crane's magnet.