Q 12-05-035JEE MainJEE Main 2024 (9 Apr, Shift 2)Easy
A straight magnetic strip has a magnetic moment of $44\ \text{A m}^2$. If the strip is bent in a semicircular shape, its magnetic moment will be ______ $\text{A m}^2$. (given $\pi = \dfrac{22}{7}$)
Numerical value type. Enter your answer.
Answer: 28
$M = m\,l$. Bent into a semicircle, the arc length $l = \pi r$ and the new pole separation is the diameter $2r = \dfrac{2l}{\pi}$:
$$M' = \frac{2}{\pi}M = \frac{2\times7}{22}\times44 = 28\ \text{A m}^2$$
Solution by Sreeraj P, M.Sc Physics