very distant, or entirely absent, or the frequency is so high that the distance to the return conductor is an appreciable portion of the wavelength. Electric drift The drift velocity deals with the average velocity of a particle, such as an electron, due to an electric field. In general, an electron will propagate randomly in a conductor at the Fermi velocity. Free electrons in a conductor follow a random path. Without the presence of an electric field, the electrons have no net velocity. When a DC voltage is applied, the electron drift velocity will increase in speed proportionally to the strength of the electric field. The drift velocity in a 2 mm diameter copper wire in 1 ampere current is approximately 8 cm per hour. AC voltages cause no net movement; the electrons oscillate back and forth in response to the alternating electric field (over a distance of a few micrometers – see example calculation). See also Speed of light Speed of gravity Speed of sound Telegrapher's equations Reflections of signals on conducting lines References Further reading Alfvén, H. (1950). Cosmical electrodynamics. Oxford: Clarendon Press Alfvén, H. (1981). Cosmic plasma. Taylor & Francis US. "Velocity of Propagation of Electric Field", Theory and Calculation of Transient Electric Phenomena and Oscillations by Charles Proteus Steinmetz, Chapter VIII, p. 394-, McGraw-Hill, 1920. Fleming, J. A. (1911). Propagation of electric currents in telephone & telegraph conductors. New York: Van Nostrand External links Propagation Times Electromagnetism Electricity