Moving Charges and Magnetism - Result Question 61
62. A current loop in a magnetic field
[2013]
(a) can be in equilibrium in one orientation
(b) can be in equilibrium in two orientations, both the equilibrium states are unstable
(c) can be in equilibrium in two orientations, one stable while the other is unstable
(d) experiences a torque whether the field is uniform or non-uniform in all orientations
Show Answer
Answer:
Correct Answer: 62. (c)
Solution:
- (c) A current loop in a magnetic field is in equilibrium in two orientations one is stable and another unstable.
$ \begin{aligned} & \because \quad \vec{\tau}=\vec{M} \times \vec{B}=M B \sin \theta \\ & \text{ If } \theta=0^{\circ} \Rightarrow \tau=0 \text{ (stable) } \\ & \text{ If } \theta=\pi \Rightarrow \tau=0 \text{ (unstable) } \end{aligned} $
