Question

When a metallic plate swings between the poles of a magnet

• A. no effect on the plate
• B. eddy currents are set up inside the plate and the direction of the current is along the motion of the plate
• C. eddy currents are set up inside the plate and the direction of the current oppose the motion of the plate
• D. eddy currents are set up inside the plate

Hint:

Eddy currents always oppose the motion/change causing them, leading to magnetic damping.

Answer 1

The Correct Option is C

Step 1: Understand electromagnetic induction in moving conductor.
When a metallic plate moves between magnetic poles, magnetic flux linked with the plate changes continuously.
Step 2: Eddy currents are induced.
Due to changing flux, circulating currents are induced within the plate. These are called eddy currents.
Step 3: Apply Lenz's Law.
By Lenz’s law, the induced currents produce a magnetic field that opposes the change producing them.
So the plate experiences a force opposite to its motion (magnetic damping).
Step 4: Conclusion.
Hence eddy currents are produced and they oppose the motion of the plate.
Final Answer:
\[ \boxed{\text{(C) eddy currents oppose the motion of the plate}} \]