b) mean drift velocity

a) mean drift velocity of charge carriers

b) I = Anev where n is the number density of charge carriers

mean drift velocity = the net velocity of electrons moving through a conductor

I = Anev

• electric current (A) = cross-sectional area of the conductor (m^2) × number density × elementary charge × velocity (ms^-1)

the mean drift velocity is inversely proportional to the cross-sectional area

• if the cross-sectional area decreases, the mean drift velocity must increase for the electric current to stay the same