Class 12 NEET Physics Magnetism and Matter Questions

Let m be strength of each pole of bar magnet of length l. Then
M=m×l..........(i)
When the bar magnet is bent in the form of an arc as shown in figure
Then l=

π

3

×r=

πr

3

or r=

3l

π

New magnetic dipole moment
M′=m×2rsin30°
=m×2×

3l

π

×

1

2

=

3ml

π

=

3M

π

  (Using (i))