In electromagnetism, mobility is a quantity that relates applied
electric field to the drift velocity of electrons in a
material. Mobility is often denoted by the Greek letter mu.
The units of mobility are (m^2)/(Vs), meters squared per volt
second. Mobility relates drift velocity to electric field with this
equation:
U = \mu E
where U is the velocity vector and E is the electric field
vector.
The mobility a given material affords electrons is usually temperature dependent. Mobility is closely related to the resistance of a material.