Magnetics 4 Question 5
6. A rectangular loop of sides $10 cm$ and $5 cm$ carrying a current $I$ of $12 A$ is placed in different orientations as shown in the figures below.
(2015 Main)
(c)
If there is a uniform magnetic field of $0.3 T$ in the positive $z$-direction, in which orientations the loop would be in
(i) stable equilibrium and (ii) unstable equilibrium?
(a) (a) and (b) respectively
(b) (b) and (d) respectively
(c) (a) and (c) respectively
(d) (b) and (c) respectively
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Answer:
Correct Answer: 6. (b)
Solution:
- Direction of magnetic dipole moment $\mathbf{M}$ is given by screw law and this is perpendicular to plane of loop.
In stable equilibrium position, angle between $\mathbf{M}$ and $\mathbf{B}$ is $0^{\circ}$ and in unstable equilibrium this angle is $180^{\circ}$.
