Question

Mention two ways by which the speed of rotation of an electric motor can be increased.

Answer 1

- add a rheostat in series with the field winding of a shunt motor. If you increase the resistance in field winding, field flux will be reduced and consequently, speed will be increased.

- you can use a rheostat in parallel with the field winding. When you decrease the parallel resistance of the field winding, current in the field branch will be divided, reducing the field flux. Thus speed will be increased.

hope it is helpful ^_^

Answer 2

The speed of rotation of an electric motor can be increased by:

(i) Increasing the strength of current.

(ii) Increasing the number of turns in the coil.