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Show, that it is impossible to explain the nature of ferromagnetism on the basis of the interaction of magnetic dipoles. |
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Answer» <P> Solution :Since the CURIC point of ferromagnetic naterials is of the order of hundreds of degrees Celsius, the energy of thermal motion is`vecepsi approx kT ....38 xx 10^(-23) xx 400 approx 5 xx 10^(-21)J` The energy of interaction of two magnetic moments is `epsi_(m)=p_(m) B =2mu_(0)v_(m)^2//4pir^3`. Putting `r approx 1A, p_(m)` we obtain `epsi_(m) approx (4pi xx 9.28^2 xx 10^(48))/(2pi xx 10^(7) xx 10^(-20)) approx 2 xx 10^(-23) J` We SEE that the intoraction energy of magnetic moments is by two orders of magnitude smaller than the energy of thermal motion, therefore inagnetic interaction is INCAPABLE of causing SPONTANEOUS magnetization inside a domain. |
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