Question

An infinitely long, straight conductor AB is fixed and a current is passed through it. Another movable straight wire CD of finite length and carrying current is held perpendicular to it and released. Neglect weight of the wire

(a) The rod CD will move upwards parallel to itself 

(b) The rod CD will move downward parallel to itself 

(c) The rod CD will move upward and turn clockwise at the same time 

(d) The rod CD will move upward and turn anti –clockwise at the same time

Answer 1

Correct option (c) The rod CD will move upward and turn clockwise at the same time

Explanation: 

Since the force on the rod CD is non-uniform it will experience force and torque. From the left hand side it can be seen that the force will be upward and torque is clockwise.