Verified Solution • 2025–26 Session
moderate
QJEEAdv20Ph2466: JEE Advanced 2020 Physics - Class 12 JEEAdv20Ph2466 Solution: A light disc made of aluminium (a nonmagnetic material) is kept …
A light disc made of aluminium (a nonmagnetic material) is kept horizontally and is free to rotate about its axis as shown in the figure. A strong magnet is held vertically at a point above the disc away from its axis. On revolving the magnet about the axis of the disc, the disc will (figure is schematic and not drawn to scale) 
Multiple Choice Options
- A rotate in the direction opposite to the direction of magnet’s motion
- B rotate in the same direction as the direction of magnet’s motion
- C not rotate and its temperature will remain unchanged
- D not rotate but its temperature will slowly rise
Step-by-Step Verified Solution
When the magnet is moved, it creates a state, where the plate moves through the magnetic flux, due to which an electromotive force is generated in the plate and eddy currents are induced. These currents are such that it opposes the relative motion disc will rotate in the direction of rotation of magnet.