PH 102 Lecture Notes - Lecture 8: Drift Velocity, Density, Electric Field
Document Summary
As discussed earlier, as the electrons travel through a conductor under the influence of an applied field, they collide with atoms and impurities and accelerate between collisions in a direction opposite to the electric field. The drift velocity is the average velocity they acquire during this acceleration, which is given by a vd qe m where is the average time between collisions. We can show that this is equivalent to writing where. The conductivity, , is the inverse of resistivity. The resistivity, (not to be confused with mass density) is a measure of the intrinsic contribution of a material to its resistance and is independent of the geometry of the material. The unit for resistivity is -m. good conductors, such as copper or silver, have low resistivity, whereas poor conductors such as carbon have high resistivity. The resistance, is related to the resistivity by:
