A domain in ferromagnetic iron in the form of cube shaving `5 xx 10^(10)` atoms. If the side length of this domain is `1.5mu` and each atom has a dipole moment of `8 xx 10^(-24)Am^(2)`, then magnetisation of domain is

Options

A. `7.2xx10^(5) Am^(-1) `
B. `7.2 xx 10^(3) Am^(-1) `
C. `7.2 xx 10^(9)Am^(-1) `
D. `7.2 xx 10^(12)Am^(-1) `

Answer

A

Explanation

Magnetisation `=("Dipole moment")/("Volume")`
`=( 8 xx 10&=^(10) xx 9 xx 10^(-24))/(10^(-18))=7.2 xx 10^(5) Am^(-1)`