A bar magnet made of steel has a magnetic moment of `2.5 A m^2` and mass of `6.6 xx 10^(-5) kg`. If the density of steel is `7.9 xx 10^3 kg m^(-3)`, find the intensity of magnetization of the magnet.

Options

A. `1.0 xx 10^(6) Am`
B. `4.0xx10^(6)Am`
C. `4.0 xx 10^(6) Am`
D. `3.0 xx 10^(6) Am`

Answer

C

Explanation

`M=2.5Am^(2),m=6.6xx10^(-3)kg,rho=7.9xx10^(3)kg/m^(3)`
I=?
`I=(M)/(V)` but `rho=(m)/(V) therefore V=(m)/(rho)`
`Now I=(M)/(m)rho`
`=(2.5xx7.9xx10^(3))/(6.6xx10^(-3))=3xx10^(6) A/m`