Electromagnet is the most powerful type of magnet there is it is a magnet with a current running through it and can be turned on and off. why might it be useful to be able to turn the electric magnet on and off? I think it's to control the strength of the magnet.
Being able to turn an electromagnet on and off allows for greater control and precision in its magnetic strength. This can be useful in various applications where varying levels of magnetism are needed, such as in magnetic levitation trains, magnetic sorting systems, and MRI machines.
Additionally, turning off the electromagnet can save energy and prevent overheating, as the current running through the electromagnet is what generates the magnetic field. By toggling the electromagnet on and off as needed, it can operate more efficiently and effectively for its intended purpose.