Q. An electron of charge $e$ moves with a constant speed $v$ along a circle of radius $r$, its magnetic moment will be
A) $evr$
B) $evr/2$
C) $\pi r^{2}ev$
D) 2$\pi rev$
Explanation
(b) Here ,area of circular orbit of electron A = $\pi r^{2}$,current due to motion of electron
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ i$= $\frac{e}{t} = \frac{e}{2\pi r/v} = \ \frac{ev}{2\pi r}$
Magnetic moment = $iA$
= $\frac{eV}{2\pi r}\ \times \ {\pi r}^{2}$
=$\frac{evr}{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.