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 $P$
• E. answer required

Answer 1

The correct option is A will be attracted toward $P$

As the conductor P moves away from Q, the area of the loop enclosed by the conductors and the rails increases. This is turn increases the flux through the loop.

EMF will be induced in such a way that the change in flux will be resisted. The induced current will cause Q to move towards P thereby reducing the area and thus the flux back.