Question

A bar magnet of length 'l' and magnetic dipole moment M is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be

(a) 2/π

(b) M/2

(c) M

(d) 3/π M

Answer 1

Correct option  (d) 3/π M

Explanation:

Let n be strength of each pole of bar magnet of length l. Then 

M = m x 1      .......(1)

When the bar magnet is bent in the form of an arc as shown in figure Then

Here arc length= rθ (θ=π/3)

So,