Question

A thin wire loop carrying a current $I$ is placed in a uniform magnetic field $B$ pointing into the plane of the coil as shown in the figure. The loop will tend to …….

• A. moves towards positive x-direction
• B. moves towards negative x-direction
• C. expand
• D. contract

Answer 1

The correct option is C

expand

1. The net force on a current-carrying loop in the uniform magnetic field is zero.
2. Hence, the loop cannot translate.
3. So, it will not move towards positive x-direction or negative x-direction.
4. On applying Fleming's left-hand rule, the thumb points outward at all points of the loop.
5. It means, the magnetic force on each element of the loop is radially outwards.
6. Therefore, the loop will have the tendency to expand.

Hence, option (c) is correct.