Question

A copper ring is suspended by a thread in a vertical plane. If one end of a magnet is brought horizontally towards the ring in the ring’s plane i.e. the ring and the loop are in the same plane as shown in the figure. Then what will the ring do?

• A. move towards the magnet.
• B. does not change its position.
• C. move away from the magnet.
• D. at first move towards the magnet and then move away from the magnet.

Answer 1

The correct option is B does not change its position.

The area of cross section as per the orientation shown in figure will not cut any magnetic field lines emanating from the magnet as the area of the coil and the magnet is perpendicular to each other.
So flux is given by the formula
$\Phi =BAcos\theta$
Therefore for $\theta ={90}^0$, the flux is zero.
Therefore the ring will not behave as a magnet as no current is induced in it and so it will not move.
Hence, option B is the correct answer