JEE Advance - Physics (2020 - Paper 1 Offline - No. 15)
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)
rotate in the direction opposite to the direction of magnet’s motion
rotate in the same direction as the direction of magnet’s motion
not rotate and its temperature will remain unchanged
not rotate but its temperature will slowly rise
Explanation
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 $$ \Rightarrow $$ disc will rotate in the direction of rotation of magnet.
Comments (0)
