Consider a metal ring kept (supported by a cardboard) on top of a fixed solenoid carrying a current I (see Fig 6.5). The center of the ring coincides with the axis of the solenoid. If the current in the solenoid is switched off, what will happen to the ring?

Question

Philoid · Accepted Answer

In this solenoid current was flowing so it will act like a magnet. Now when current is switched off, magnetic flux decrease so induced current produced in ring in such a way so that it can increase the flux because of Lenz’s law. So north-pole is produced in ring in lower side, and attracted by solenoid. And fixed ring will also not able to shift downward.