Did you know that Why It Is Not Possible To Measure The Drift Speed For Electron By Timing Their Travel Along A Conductor? If you don’t know about it then don’t worry because we will give you the correct reason for this question.
Since speed is the distance travelled by a body in unit time. But in the case of the drift speed of electrons, this formula is not accurate, the drift speed of electrons is very low. When a conductor is connected to a voltage source, the randomly moving electrons start moving in a proper direction due to the electric field created by the source.
These electrons collide with one another and also with the atoms of the conductor. Due to this collision, the electrons do not move on a straight path rather they move on a zigzag path with increasing and decreasing speed.
So, the electrons do not cover the appreciable distance in time t. This is the reason that we cannot measure the drift velocity for electrons by timing their travel along a conductor.