Question

what do you mean by mobility of electrons?write its SI units?

Answer 1

Electron mobility, basically, is a measure of the ability of an electron to respond in the presence of external electric field (when applied to a material, say, a conductor) or how quickly it moves through a conductor from one point to another in such a case.

Mathematically, it is defined as the ration of the drift velocity of an electron with respect to the magnitude of the external electric field applied.