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.

(a) When current is passed through the winding of the solenoid, current at end X is in anticlockwise direction so it becomes the North pole. The current at end Y is in clockwise direction so it becomes the South pole.

(b) One way of increasing the strength of electromagnet so formed is by reducing resistance of circuit by means of rheostat to increase current in the coil.