A straight wire carrying a current is turned into a circular loop if the magnitude of magnetic moment associated with it is M then the length of the wire will be

Options

A. `(M oi)/(4i)`
B. `sqrt(4pi i)/(M)`
C. `sqrt((4pi M)/(i))`
D. `4pi iM`

Answer

C

Explanation

The magnetic moment (M) of a circcular loop is
`M=iA=ixxpir^(2)`
Buut L= `2pir therefore =(L)/(2pi)`
`therefore L^(2)=(4Mpi)/(i) therefore L=sqrt(4piM)/(i)`