For a circular coil magnetic moment is M r is the radius and L is the length of the coil then M is proportional to

Options

A. `L^(0)`
B. `N^(1)`
C. `L^(2)`
D. `L^(3)`

Answer

C

Explanation

For the circular coil `2pir=L therefore r=(L)/(2pi)` and the magnetic moment
M=IA but `A= pir^(2)`
`I.pir^(2)=I.(L^(2))/(4pi^(2))`
`therefore M=(L^(2)I)/(4pi) therefore M prop L^(2)`