A long thin magnet of moment `M` is bent into a semi circle. The decrease in the magnetic moment is

Options

A. `2M//pi`
B. `piM//2`
C. `M(pi-2)//pi`
D. `M(2-pi)//2`

Answer

C

Explanation

For semi circle, `M^(1)=(2M)/pi`
decrease in M, `DeltaM=M-M^(1)`