a) How does an electromagnet differ from a permanent magnet?
b) Name two devices in which electromagnets are used and two devices where permanent magnets are used.

Answer:

a) When compared to a permanent magnet, an electromagnet differs in that an electromagnet may produce a magnetic field as long as the current is running through it, whereas a permanent magnet does not require electric current for the generation of the magnetic field.

b) Electric bells and electric motors are examples of electromagnets. Toys and refrigerator doors are both held together by permanent magnets.