Question

A metal ring kept (supported by a card board) on the top of a fixed solenoid carry a current I as shown in figure. The centre of the ring coincides with the axis of the solenoid. If the current in the solenoid is switched off, then

• A. magnetic flux linked with the metal ring increases.
• B. current induced in the metal ring in clockwise direction.
• C. metal ring will not remain on the cardboard
• D. both (a) and (b) are correct.

Answer 1

Answer: (B)

current induced in the metal ring in clockwise direction.

When the current in the solenoid is switch off magnetic flux linked with the solenoid and hence with metal ring decreases. Current induced in the metal ring is clockwise, i. e in the same direction as the solenoid current. so, they will attract each other. therefore, the metal ring will remain on the cardboard.