# Error in drift Formula of Current?

1. Aug 8, 2010

### tan99

Error in drift Formula of Current??

Drift velocity, vd = eEτ/me

Drift velocity, as in the current formula I=nevdA should correspond to the average velocity with which the electrons are moving in the steady current, but the formula at top gives the mean FINAL velocity achieved by the electrons in short spurts of time(mean relaxation time, τ).
Since distance d=0.5aτ2 , the average velocity

v=d/τ=0.5eEτ/me

Shouldn't this be a better formula??

PS: The average initial velocity u is 0 I believe...