A wire of length `2 m` carrying a current of `1 A` is bend to form a circle. The magnetic moment of the coil is (in `A-m^(2)`)

Options

A. `2pi`
B. `pi/2`
C. `pi/4`
D. `1/pi`

Answer

D

Explanation

Magnetic moment `=IA`
But `A=pi r^(2)` where `r=L/(2pi)`
`:. A=pi (L^(2)/(4pi^(2)))=L^(2)/(4pi)`
`:. M=IA =(L^(2) I)/(4pi)=(2xx2xx1)/(4pi)=1/pi`
`:. M=1/pi Am^(2)`