What is a magnet that can be turned on and off by controlling the electric current flowing through it called?

A magnet that can be turned on and off by controlling the electric current flowing through it is known as an electromagnet. This is achieved by wrapping a coil of wire around a ferromagnetic material and passing an electric current through the wire. When the current flows, a magnetic field is generated, magnetizing the material and making it behave like a magnet. When the current is stopped, the magnetic field disappears, and the metal no longer has magnetic properties.

This functionality of being able to switch the magnetism on and off with an electric current is what distinguishes electromagnets from permanent magnets, which always have a magnetic field without an external power source. The ability to control the strength and presence of the magnetic field makes electromagnets highly useful in various applications, including electric motors, magnetic locks, and loudspeakers.