Question

Assertion :A small coil carrying current, in equilibrium, is perpendicular to the direction of the uniform magnetic field. Reason: Torque is maximum when plane of coil and direction of the magnetic field are parallel to each other.

• A. Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
• B. Both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Assertion is incorrect but Reason is correct.

Answer 1

The correct option is B Both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

The torque acting on a coil is proportional to the angle between the plane of the coil and the direction of magnetic field. When angle $={90}^o$, then torque $=0$. The coil tries to orient itself in this position. Thus in equilibrium, the coil acquires a position, such that its plane makes an angle ${90}^o$ with the direction of magnetic field.