If you take an insulated wire and attach one end to the end of a battery, then wrap that wire multiple times around an iron nail, then attached the other end to the opposite end of the battery, what you get is an electromagnet. The iron nail is magnetized through induction as its domains line up with the magnetic field produced by the current-carrying wire. The result is that you can pick up magnetic objects with that nail.
An ordinary magnet cannot be turned off, but turning off the current in an electromagnet turns off the magnet. Being able to turn off a magnet can be useful practically speaking. For example, think of a junk yard where a large electromagnet is used to pick up old cars and move them to a new location. After it has picked the car up and moved it, the operator can just turn off the magnet and the car is released. In a doorbell, you hold the doorbell button and current will flow through the electromagnet. But when you release the button, the current will stop flowing through the electromagnet and the magnetic field will collapse.
Another application of electromagnets is in particle physics and transportation.
Question
What are the advantages of an electromagnet?
You can increase and decrease the magnetic strength as well as turn it off and on.
