Q 12-04-030JEE MainMedium
A current loop of magnetic moment $2\ \text{A m}^2$ is in a uniform magnetic field of $0.3$ T. Find the work (in J) needed to turn it from its stable equilibrium position to its unstable equilibrium position.
Numerical value type. Enter your answer.
Answer: 1.2
Potential energy $U = -MB\cos\theta$. Stable: $\theta = 0$, $U = -MB$. Unstable: $\theta = 180^\circ$, $U = +MB$.
$W = 2MB = 2 \times 2 \times 0.3 = 1.2$ J.
Solution by Sreeraj P, M.Sc Physics