- #1
Jimmy87
- 686
- 17
I have recently been learning about the microscope properties which dictates electrical resistance. The main equation (resistivity) in my textbook is:
[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
[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