A light metal disc on the top of an electromagnet is thrown up as the current is switched on. Why? Give reason.

Explanation

Let at the top end of the electromagnet, the current in the coil is clockwise when observed from above. As per Lenz's law, eddy current is induced in the metal disc in such a direction that it would tend to neutralise the current, at this instant the current is switched on. So the eddy current will be anticlockwise. As unlike parallel currents repel each other, the metal disc is thrown up.