Question

An insulated rod of length $l$ carries a charge q uniformly distributed on it.The rod is pivoted at one of its ends and is rotated at a frequency $f$ about a fixed perpendicular axis.The magnetic moment of the rod is

• A. $\frac{\pi qf{l}^2}{12}$
• B. $\frac{\pi qf{l}^2}{2}$
• C. $\frac{\pi qf{l}^2}{6}$
• D. $\frac{\pi qf{l}^2}{3}$

Answer 1

The correct option is D $\frac{\pi qf{l}^2}{3}$

$\frac{M}{L}=\frac{q}{2m}$

$M=(\frac{q}{2m}\left)\right(I\omega \left)\right(\frac{m{l}^2}{3}\left)\right(2\pi f)$
$=\frac{\pi qf{l}^2}{3}$