- #1

Asrai

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Anyway, the problem is as follows:

*Point defects in metals can cause additional electrical resistivity at low temperatures due to extra electron scattering which is proportional to the number of defects. The table gives the relative change in the resistivity at 78 K of a gold wire when it is quenched from various temperatures:*

Temp K 920 970 1020 1060 1220

Resistivity Change 0.41% 0.7% 1.4% 2.3% 9.0%

Calculate the energy of formation of a vacancy in gold.

Temp K 920 970 1020 1060 1220

Resistivity Change 0.41% 0.7% 1.4% 2.3% 9.0%

Calculate the energy of formation of a vacancy in gold.

So, I've spent some time on this problem, using the equation n/N = exp(-E/(k*T)), where n is the number of defects, N the number of atoms and E is the energy of formation.

Seeing as resistivity change is directly proportional to n/N, I divided the percentages by a hundred and put them into the formula. Putting in the different temperatures and resistivity changes gives me five different values for the energy of formation in the ordner of magnitue of 10^-20.

Now, I think the question asks me to calculate the energy of a single vacancy, but I'm not too sure about that. And if that is indeed the case, how could I calculate it? In that case n would be 1, but seeing as I don't have N, how do I solve the equation?

Any help would be greatly appreciated!