Question

Two identical conductors $P$ and $Q$ are placed on two frictionless rails $R$ and $S$ in a uniform magnetic field directed into the plane. If $P$ is moved in the direction shown in figure with a constant speed, then rod $Q$ .

• A. Will be attracted toward P
• B. Will be repelled away from P
• C. Will remain stationary
• D. May be repelled away or attracted toward P

Answer 1

The correct option is A

Will be attracted toward P

The explanation for the correct option:

In the case of option A.

1. As the conductor P moves away from Q, the area of the loop enclosed by the conductors and the rails increases.
2. This in turn increases the flux through the loop.
3. EMF will be induced in such a way that the change in flux will be resisted.
4. The induced current will cause Q to move towards P thereby reducing the area and thus the flux.

The explanation for incorrect options:

In the case of option B,

1. By the concept of electromagnetic induction, the above statements are not qualified.
2. From Lenz's law if one rod is moved away from the second rod then the second rod will be attracted toward the first rod to oppose the change in flux.

In the case of option C,

1. The induced current will cause Q to move towards P.
2. Thereby reducing the area and thus the flux back. So, Rod Q will not remain stationary.

In the case of option D,

1. The induced current will cause Q to move towards P but may be repelled away.
2. Therefore option(D) is incorrect.

Therefore option(A) is correct