State two differences between an electromagnet and a permanent magnet.

State two advantages of an electromagnet over a permanent magnet.

The diagram in figure. shows a coil wound around a soft iron bar XY. (a) State the polarity at the end X and Y as the switch is pressed. (b) Suggest one way of increasing the strength of electromagnet so formed.

What is an electromagnet? Name two factors on which the strength of magnetic field of an electromagnet depends and state how does it depend on the factors stated by you.