Derive the Drift Velocity Equation

(The drift velocity is the average velocity of a charge carrier due to an electric field)Consider a conductor with length l and cross sectional area AThere are n electrons per unit volume (m3) moving through the conductor with drift velocity vThe distance travelled by an electron travelling at speed v in time dt is: l = vdtThe volume of the conductor is: V = AlTherefore V = A*(vdt)Since n is the number of electrons per m3 , the total number of electrons in that section of the conductor is = nA*(vdt)so the total charge Q = nAvdte (where e is charge on 1 electron)Since current is defined as I = Q/dtI = (nAvdte)/dt and the "dt" cancels out leaving you with the equation for drift velocity in a conductor:I = nAve

FM
Answered by Francois M. Physics tutor

4377 Views

See similar Physics A Level tutors

Related Physics A Level answers

All answers ▸

What is Coulomb's law


A student is measuring the acceleration due to gravity, g. They drop a piece of card from rest, from a vertical height of 0.75m above a light gate. The light gate measures the card's speed as it passes to be 3.84 m/s. Calculate an estimate for g.


Two trains are heading in opposite directions on the same track. Train X has a mass of 16000kg and a speed of 2.8m/s. Train Y has a mass of 12000kg and a speed of 3.1m/s. At what speed do the joined trains move off together immediately after the collison?


A phone is knocked off a table 800cm of the ground. If the phone is 650g a) what is the gravational potential of the phone? b)what speed will the phone hit the floor at? c)How long will it take for the phone to hit the floor?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2026 by IXL Learning