Question

A magnetic needle lying parallel to the magnetic field requires \( W \) units of work to turn it through an angle 45°. The torque required to maintain the needle in this position will be

• A. \( \sqrt{W} \)
• B. \( 1 \)
• C. \( \sqrt{3}W \)
• D. \( \frac{W}{\sqrt{2}} \)

Hint:

For a magnetic needle, the torque is related to the work done when the needle moves through an angle.

Answer 1

The Correct Option is D

The torque required to maintain the needle in the magnetic field is calculated by using the work-energy theorem and the angle of deflection. The work done by the magnetic field is related to the torque by \( \tau = \frac{W}{\theta} \).