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Question
A coil is suspended in a uniform magnetic field, with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil it starts oscillating: It is very difficult to stop. But if an aluminium plate is placed near to the coil, it stops. This is due to:
Options
development of air current when the plate is placed.
induction of electrical charge on the plate.
shielding of magnetic lines of force as aluminium is a paramagnetic material.
electromagnetic induction in the aluminium plate giving rise to electromagnetic damping.
Solution
electromagnetic induction in the aluminium plate giving rise to electromagnetic damping.
Explanation:
Because of the Lenz's law.
Al will experience an emf that opposes the emf's cause, an oscillating coil.
