A bar magnet has length 3 cm, cross-sectional area `2 cm^(3)` and magnetic moment `3 Am^(2)`. The intensity of magnetisation of bar magnet is

Options

A. `2 xx 10^(5) A//m`
B. `3 xx 10^(5) A//m`
C. `4 xx 10^(5) A//m`
D. `5 xx 10^(7) A//m`

Answer

D

Explanation

Given , `L = 3 cm = 3 xx 10^(-2)m`
`A = 2 cm^(2) = 2 xx 10^(4) m^(2)`
`M = 3 Am^(2)`
Intensity of magnetisation `= M/(L xx A)`
`= (3A. M^(2))/( 3 xx 2 xx 10^(-6) m^(3))`
`= 1/2 xx 10^(6) A//m = 5 x 10^(5) A//m`