Question

A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It

• A. Will stay in its position, showing no movement
• B. Will stay in north-west direction only
• C. Will stay in north-south direction only
• D. Will stay in east-west direction only

Answer 1

The correct option is A Will stay in its position, showing no movement

At the geomagnetic poles, the field lines will be vertical.
But the plane of needle is horizontal.


At the poles, horizontal component of the field $=0$ and the vertical component will not affect the needle.

So, there will be no driving torque acting on the needle and it will stay in its position and exhibit no movement.

Hence, option $\left(A\right)$ is the correct answer.