A straight wire carring current I is turned into a circular loop. If the magnitude of magnetic moment associated with it in M.K.S. unit is M, the length of wire will be

Options

A. `(4pi)/(M)`
B. `(Mpi)/(41)`
C. `sqrt((4piM)/(1))`
D. `sqrt((4piI)/(M))`

Answer

C

Explanation

M=IA
`M=Ipir^(2)`
`therefore r=sqrt((M)/(piI))`
length of wire=`l=2pir`
`l=2pisqrt((M)/(pil))`
`=sqrt((M4pi^(2)))/(piI)`
`sqrt((4piM)/(I))`