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

Question

A long thin magnet of magnetic moment M is bent into a semi-circle. The decrease in the magnetic moment is (A) (2 M/π ) (B) (π M/2) (C) (M (π - 2)/π ) (D) (M (2 - π )/2)

Tardigrade Admin · Accepted Answer

Magnetic length is the minimum distance between the north pole and the south pole, which is decreased in the second case. Mâ²=(2 M/π ) , decrease in magnetic moment =M-(2 M/π )

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

$\frac{2 M}{π}$

$\frac{π M}{2}$

$\frac{M ( π - 2 )}{π}$

$\frac{M ( 2 - π )}{2}$

Magnetic length is the minimum distance between the north pole and the south pole, which is decreased in the second case.
$M^{'} = \frac{2 M}{π}$ , decrease in magnetic moment
$= M - \frac{2 M}{π}$

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

π2M​

2πM​

πM(π−2)​

2M(2−π)​