(a) An electromagnet is a kind of magnet where the magnetic field is created by an electric current.
Uses of electromagnate are :
(i) Generators, motors and transformers.
(ii) Electric buzzers and bells
(c) The soft iron inside the coil makes the magnetic field stronger because it becomes a magnet itself when the current is flowing. Soft iron is used because it loses its magnetism as soon as the current stops flowing. Soft iron is said to form a temporary magnet. In this way, the electromagnet can be switched on and off by turning the electricity on and off.

(d) The strength of an electromagnet depends on :

(i) Increasing the strength of the current passing through the coil, the greater the current, the greater the strength.

(ii) Increasing the number of turns in the coils, the greater the number of turns, the greater the strength.

(iii) Whether the core is made up of a soft or hard magnetic material. Soft iron will magnetise more readily than steel. Therefore, using a soft core increase the strength of the electromagnet.