Question

The torque of a conductor is defined only in the case when

(a) The field is perpendicular to the loop

(b) The plane of the loop is parallel to the field

(c) The plane of the loop is perpendicular to the current direction

(d) The field and the current direction are same

I have been asked this question in exam.

Origin of the question is Magnetic Torque topic in portion Magnetic Forces and Materials of Electromagnetic Theory

Answer 1

Correct choice is (b) The plane of the loop is parallel to the field

To explain: The torque of a conductor is given by T = NBIA. This equation of the conductor is valid only when the plane of the loop is parallel to the magnetic field applied to it.