An iron rod of length L and magnetic moment M is bent in the form of a semicircle. Now its magnetic moment will be

Options

A. 4 M
B. `M//4`
C. `2M//pi`
D. 2 M

Answer

C

Explanation

When it is bent into a semicircle `L=pi r therefore r=(L)/(pi)`
`therefore` New magnetic length `=2r(2L)/(pi)`
`therefore` New mgnetic moment =`(2M)/(pi)`