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. `3 xx 10^(5) A//m`
B. `4xx 10^(5) A//m`
C. `2 xx 10^(5) A//m`
D. `1 xx 10^(5) A//m`

Answer

D

Explanation

Given `l = 5 cm = 5 xx 10^(-2)m`,
`a = 2 cm^(2) = 2 xx 10^(-4) m^(-2)`
`a = 2 cm^(2) = 2 xx 10^(-4) m^(2)`
and `M = 1 Am^(-2) `
The magnetisation of the bar magnet is given by `I =(M)/(V)`
where V = volume of bar magnet `= a xx l`
`rArr " " i = (M)/(a xx l)`
Substituinting given values , we get
`I =(1)/(2xx 10^(-4) xx 5 xx 10^(-2)) =(1)/(10^(-5))`
` = 1xx 10^(5) A//m`