Question

$AB$ and $CD$ are fixed conducting smooth rails placed in a vertical plane and joined by a constant current source at its upper end. $PQ$ is a conducting rod which is free to slide on the rails. A horizontal uniform magnetic field exists in space as shown. If the rod $PQ$ is released form rest, then :

• A. the rod $PQ$ will move downward with constant acceleration
• B. the rod $PQ$ will move upward with constant acceleration
• C. the rod will remain at rest
• D. any of the above

Answer 1

The correct option is D any of the above

As two parallel wire carrying current in same direction attract each other.

Depending upon the magnitude of induced current in rod PQ due to vertical motion, the rod will either move upward with constant acceleration if attraction force is greater than its weight and vice-versa or may remain at rest if the attraction force balances its weight.