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 plane of ring as shown, the ring will

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

Answer 1

The correct option is B not change its position.

Answer is B.

The magnetic flux is given by $\varphi =BAcos\theta$ where $\theta$ is angle between magnetic field and area of ring.

in this case the area vector is out of the plane, hence $\theta ={90}^{\circ }$,

$\Rightarrow \varphi =0$

The ring will not move from the magnet, as there is no change in flux through ring and current in it will be zero. Ring will not behave as a magnet.