I have recently been learning about the microscope properties which dictates electrical resistance. The main equation (resistivity) in my textbook is:(adsbygoogle = window.adsbygoogle || []).push({});

[itex]\rho[/itex] = 2m/qN[itex]\tau[/itex] where [itex]\tau[/itex] is the time between collisions of electrons with the atoms, q is the charge of the electron, N is the number of free electrons and m is the mass of the electron.

These properties are fixed for a given material. I am quite comfortable with why certain materials have more free electrons than others. But I was wondering if anyone knows what determines the time between collisions for a resistor ([itex]\tau[/itex]). Say if a certain material has less time between collisions then what is it about the material that determines this? Is it to do with the density of the material, so a more dense material has more atoms per unit volume so there would be less time between collisions?

Thanks for any help

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# Microscopic properties of electrical resistance

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