The length of a magnetised steel wire is l is the magnetic momemt is M. It is bent the shape of L with two sides equal. What will be the new magnetic moment?

Options

A. 2M
B. `M//2`
C. `sqrt(2)M`
D. `M//sqrt(2)`

Answer

D

Explanation

If m is strength of each pole, then magnetic moment `M=mxx l`

When the wire is bent into L shape , effective distance between the poles
`=sqrt(((l)/(2))^(2)+((l)/(2))^(2))=(l)/(sqrt(2))`
` :.` New mangetic moment , `M'=mxx(l)/(sqrt(2))=(M)/(sqrt(2))` (m will remain unchanged )