Consider a metal ring kept on top of a fixed solenoid (say on a cardboard) as per the figure. The center of the ring coincides with the axis of the solenoid. If the current is suddenly switched on,the metal ring jumps up. Explain.

(N/A) Initially,there is no magnetic flux linked with the metal ring.
When the current is suddenly switched on,the magnetic field produced by the solenoid increases rapidly.
According to Faraday's law of electromagnetic induction,this change in magnetic flux induces an electromotive force $(EMF)$ and consequently an induced current in the metal ring.
According to Lenz's law,the direction of this induced current is such that it opposes the cause that produced it,which is the increasing magnetic flux.
Therefore,the induced current in the ring flows in a direction opposite to the current in the solenoid.
Due to this,the ring and the solenoid act like two magnets with like poles facing each other,resulting in a repulsive force.
This repulsive force causes the metal ring to jump up.