Consider a metal ring kept on top of a fixed solenoid (say on a carboard). The center of the ring coincides with the axis of the solenoid.
Assertion: If the current is suddenly switched on in a solenoid, the metal ring jumps up. 
Reason : Emf is induced in metal ring, such that it opposes external flux change. Due to induced current metal ring jumps up.

No flux was passing through the metal ring initially. When the current is switched on, flux passes through the ring. According to Lenz’s law this increase will be resisted and this can happen if the ring moves away from the solenoid. One can analyze this in more detail (Fig 6.5). If the current in the solenoid is as shown, the flux (downward) increases and this will cause a counterclockwise current (as seen from the top in the ring). As the flow of current is in the opposite direction to that in the solenoid, they will repel each other and the ring will move upward.