The speed of electrons inside a conductor can be understood in two different ways: the drift velocity and the random (thermal or Fermi) velocity.
- Drift velocity, which is the average velocity of electrons when an electric field is applied, is very slow—typically on the order of about 1 millimeter per second (mm/s) or even smaller (tens of micrometers per second, around 10^-3 m/s). This slow drift velocity is responsible for the actual electric current in the conductor.
- However, the electrons move randomly with very high speeds due to their thermal energy, known as the Fermi velocity. This speed is much faster, on the order of millions of meters per second (roughly 10610^6106 m/s), but this motion does not contribute to net charge flow since it is random.
- The electrical energy itself propagates as electromagnetic waves through the conductor at near the speed of light, which is much faster than the electron drift speed.
In summary, electrons inside a conductor drift slowly with a speed around 10−310^{-3}10−3 m/s under an electric field (drift velocity), while their random thermal speeds are about 10610^6106 m/s. The electric signal propagation, carried by electromagnetic waves in the conductor, happens close to the speed of light.
