Electromagnet: A device that utilizes the magnetic effect of current to make soft iron (the inner core of the electromagnetic coil, which can be quickly magnetized and demagnetized) magnetic.

(1) Insert a soft iron rod into a spiral coil, and when there is current flowing through the coil, the magnetic field inside the coil magnetizes the soft iron rod into a temporary magnet. However, when the current is cut off, the magnetism of the coil and soft iron rod disappears.

(2) The magnetic field generated by magnetization of a soft iron rod, combined with the magnetic field inside the original coil, greatly enhances the total magnetic field strength, so the magnetic force of an electromagnet is greater than that of a natural magnet.

(3) The higher the current of a spiral coil, the more coils it has, and the stronger the magnetic field of the electromagnet.