Question

A wire of length L metre carrying a current of i ampere is bent in the form of a circle Its magnetic moment will be

• A. $\frac{iL}{4\pi }$
• B. $\frac{i{L}^2}{4\pi }$
• C. $\frac{i^2{L}^2}{4\pi }$
• D. $\frac{i^{2}L}{4\pi }$

Answer 1

The correct option is B $\frac{i{L}^2}{4\pi }$

$L=2\pi r$

$r=\frac{L}{2\pi }$

magnetic moment=i.A

=$i.\pi .r^2$

=$i.\pi .\left({\frac{L}{2\pi }}^2\right)$

=$\frac{i.L^2}{4\pi }$