Question

A magnet of magnetic moment M and pole strength m is divided in two equal parts, then magnetic moment of each part will be 

(a) M 

(b) (M/2) 

(c) (M/4) 

(d) 2 M

Answer 1

 The correct option (b) (M/2)

Explanation:

(1) when a magnet is divided in n equal parts, then magnetic moment of each part is (M/n)

Here n = 2 hence magnetic moment is (M/2).

 OR

(2) [case i] if cut along axis of magnet of length ℓ then new pole strength

= m' = (m/2) and new length ℓ' = ℓ

∴ New magnetic moment = M' = m'ℓ' = (m/2)ℓ = (mℓ/2) = (M/2)

[case ii] if cut perpendicular to axis of magnet of length ℓ then new pole

strength m' = m and length ℓ' = (ℓ/2)

∴ M' = m'ℓ' = (mℓ/2) = (M/2).