A domain in a ferromagnetic substance is in the form of a cube of side length 1 `mu`m. If it contains `8 xx 10^(10)` atoms and each atomic dipole has a dipole moment of `9 xx 10^(-24) Am^(2)`, then magnetization of the domain is

Options

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

Answer

A

Explanation

Volume = `(10^(-6))^(3)= 10^(=-18) m^(3)`
Net deipole moment-
`m_("net") = 8 xx 10^(10) xx 9 xx 10^(-24)`
`= 72 xx 10^(-14) A m^(2)`
Magnetization `M= (m_("net"))/("Volume") = (72 xx 10^(-14))/(10^(-18))`
`=72 xx 10^(4)= 7.2 xx 10^(5) A//m`