The magnetic moment produced in a substance of `1 gm is 6xx10^(-7) "ampere","metre"^(2)`. If its density is `5 gm//cm^(3)`, then the intensity of magnetisation in `A//m` will be

Options

A. `1.3 xx 10^(6)`
B. 3
C. `1.2 xx 10^(-7)`
D. `3 xx 10^(-6)`

Answer

B

Explanation

Intensity of magnetisation, `(I) = M/V`
`I = M/("mass/ Density")`
Density `=5g//cm^(3) = (5 xx 10^(-3) kg)/(10^(-2))^(2) = 5 xx 10^(2) kg//m^(2)`
`I = (6 xx 10^(-3) xx 5 xx 10^(3))/10^(-3) = 3 Am^(-1)`