Magnetic moment of an electron of charge `e` moving in a circular orbit of radius `r` with speed `v is given by

Options

A. `evr`
B. `(evr)/4`
C. `(evr)/2`
D. `(evr)/2`

Answer

C

Explanation

The period of revolution of the electron is given by `T=(2pir)/v`
The current due to orbital motion of electron is
`I=q/T=e/((2pir)/v)=(ev)/(2pir)`
The magnetic moment of the revolving electron is
`M=IA=(ev)/(2pir)(pir^(2))=(evr)/2`