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A domain if ferromagnetic iron is in the form of cube of side length 1mum. Estimate the number of iron atoms in the domain and the maximum possible moment and magnetisation of the domain. The molecular mass iron is 55 g/mol and its density is 7.9g//cm^3 . Assume that each iron atom has a dipole moment of 9.27xx10^(-24) Am^2. |
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Answer» Solution :The volume of the cubic domain is V = `(10^(-6)m) ^3=10^(-18)=10^(-12)cm^3` Its MASS is volume `xx` DENSITY `=7.9"g cm"^(-3) xx10^(-12)cm^3=7.9xx10^(-12)` g It is given that Avogadro number `(6.023xx10^(23))/(55) =8.65xx10^(10)` atoms. The maximum possible dipole moment `m_(max)` is achieved for the (unrealistic) CASE when all the atomic moments are PERFECTLY aligned. Thus, `m_(max)= 8.65x10^(10)xx(9.27xx10^(-24))=8.0xx10^(-13)Am^2` The consequent magnetisation is `M_(max)=(m_(max))/("Domain volume")` `=8.0xx10^(-13)Am^2//10^(-18)m^3=8.0xx10^(5)Am^(-1)` |
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