## In This post you will get answer of Q.

A straight wire carrying current I is made into a circular loop. If M is the magnetic moment associated with the loop, then the length of the wire is

Solution:

## Magnetic moment $M=I A$

According to question,

$2 pi R =L $

$pi R =frac{L}{2}$

$M =frac{I}{pi} pi^{2} R$

$=Ileft(frac{L}{2}right)^{2} $

$M =frac{I}{pi}left(frac{L}{2}right)^{2}$

$M =frac{I}{pi} frac{L^{2}}{4}$

Length of the wire, $L=sqrt{frac{4 M pi}{I}}$