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 the coil, it stops. This is due to

• A. development of eddy current when the plate is placed
• B. induction of electrical charge on the plate
• C. shielding of magnetic lines of force
• D. aluminium is a paramagnetic material

Hint:

Eddy currents always oppose the motion that produces them, leading to magnetic damping.

Answer 1

The Correct Option is A

Step 1: When the coil oscillates near the aluminium plate, the magnetic flux linked with the plate changes. Step 2: Changing magnetic flux induces eddy currents in the aluminium plate. Step 3: According to Lenz’s law, these eddy currents oppose the motion of the coil. Step 4: The opposing force causes electromagnetic damping, stopping the oscillations.