The diagram in the figure shows a coil wound around a soft iron bar XY.
(a) State the polarity at the ends X and Y as the switch is pressed.
(b) Suggest one way of increasing the strength of electromagnet so formed.
(a) X - North pole, Y – South pole
(b) The strength of the electromagnet can be increased by reducing resistance of the circuit by means of the rheostat, thus increasing the current.