An electromagnet is a type of magnet whose magnetic field is produced by the flow of electric current. The magnetic field disappears when the current is removed. Electromagnets are very widely used as components of other electrical devices, such as motors, generators, relays, loudspeakers, hard disks, MRI machines, and scientific instruments, and as well as being employed as industrial lifting electromagnets for picking up and moving heavy iron objects like scrap iron. Electromagnets attract paper clips when current is applied to create a magnetic field. The electromagnet loses them when the current, and thus the magnetic field, are removed. The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be rapidly manipulated over a wide range by controlling the amount of electric current. However, a continuous supply of electrical energy (6 - 12 volts) is required to maintain the field. The coil and its core are mounted on a very stable plastic base. Fitted with an "on-off" switch. Connection to the electrical circuit via two 4 mm safety terminals. Base measures 100mm length by 70mm width.