What is the difference between a bar magnet and an electromagnet? (check all that are true)
A . A bar magnet is a permanent magnet that will keep its magnetism for a long time
B . An electromagnet is always stronger than a bar magnet.
C . A bar magnet will only stay a magnet if it is in contact with something metal.
D . An electromagnet is a temporary magnet that is only magnetic when electricity is flowing through the wire.