> I thought that the speed of electricity, actually electrons in a cable for a consumer use was around 1cm/s. Folks who worry about the velocity of electrons w

> I thought that the speed of electricity, actually electrons in a cable for a consumer use was around 1cm/s. Folks who worry about the velocity of electrons when discussing the velocity of signal propagation in a coax cable have not fully understood Maxwell's Equations. The fields are responsible for the propagation, and the geometry + dielectric determine the speed of the fields in the cable to first order. If those fields were in the visible, as they are for some fiber, then folks would talk about the speed of light in the coax. Since they are not in the visible, we talk about the speed of the TEM mode instead. EDIT: Some other folks are pointing out that the speed of propagation in coax is about 2/3 the speed of light. This has nothing to do with the velocity of electrons in the metal. Most coax has a central conductor, an insulator (made of teflon PTFE), and a outer conductor (the shield). The speed is almost entirely determined by the index-of-refraction of the teflon, which is approximately 1.5. The propagation speed is 1/index (approximately), so the the reciprocal of 3/2 gets you to 2/3.