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.

Mo*bil"i*ty (?), n. [L. mobilitas: cf. F. mobilit'e.]

1.

The quality or state of being mobile; as, the mobility of a liquid, of an army, of the populace, of features, of a muscle.

Sir T. Browne.

2.

The mob; the lower classes.

[Humorous]

Dryden.