An electron moves with a constant speed v along a circle of radius r. Its magnetic moment will be ______ . (e is the electron's charge.)

Options

A. evr
B. `1/2evr`
C. `pir^(2)ev`
D. `2pirev`

Answer

B

Explanation

N = 1
`A=pir^(2)`
Magnetic moment m = NIA
`thereforem=I(pir^(2))`
An electron moves with a constant speed v along a circle of radius r. The current produced,
`I=(ev)/(2pir)`
`thereforem=(ev)/(2pir)xxpir^(2)`
`thereforem=1/2evr`