I'm brushing up on auto and diesel electrical systems, and this is a weird question, but given zero resistance, and the right conductor, how fast does AC, then DC, move? I hear about the speed of light, and sound, but what about electricity?
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Close to the speed of light. Usually between 0.5 and 0.99 x the speed of light.
wikipedia:
The velocity and the electrical resistance outside of conduction is often assumed by the propagation speed of an electromagnetic wave. In simplified systems, the speed of electricity is given as the electromagnetic wave which conveys information (data), not the movement of electrons. Electromagnetic wave propagation is fast and depends on the dielectric constant of the material. In a vacuum the wave travels at the speed of light and almost that fast in air. Propagation speed is affected by insulation, such that in an unshielded copper conductor range 95 to 97% that of the speed of light, while in a typical coaxial cable it is about 66% of the speed of light.
BUT if you are asking about the actual speed of an electron in a wire, then it is much much slower, mm per hour.
wikipedia:
The drift velocity deals with the average velocity that a particle, such as an electron, attains due to an electric field. In general, an electron will 'rattle around' in a conductor at the Fermi velocity randomly. Free electrons in a conductor vibrate randomly, but without the presence of an electric field there is no net velocity. When a DC voltage is applied the electrons will increase in speed proportional to the strength of the electric field. These speeds are on the order of millimeters per hour. AC voltages cause no net movement; the electrons oscillate back and forth in response to the alternating electric field.
wikipedia:
The velocity and the electrical resistance outside of conduction is often assumed by the propagation speed of an electromagnetic wave. In simplified systems, the speed of electricity is given as the electromagnetic wave which conveys information (data), not the movement of electrons. Electromagnetic wave propagation is fast and depends on the dielectric constant of the material. In a vacuum the wave travels at the speed of light and almost that fast in air. Propagation speed is affected by insulation, such that in an unshielded copper conductor range 95 to 97% that of the speed of light, while in a typical coaxial cable it is about 66% of the speed of light.
BUT if you are asking about the actual speed of an electron in a wire, then it is much much slower, mm per hour.
wikipedia:
The drift velocity deals with the average velocity that a particle, such as an electron, attains due to an electric field. In general, an electron will 'rattle around' in a conductor at the Fermi velocity randomly. Free electrons in a conductor vibrate randomly, but without the presence of an electric field there is no net velocity. When a DC voltage is applied the electrons will increase in speed proportional to the strength of the electric field. These speeds are on the order of millimeters per hour. AC voltages cause no net movement; the electrons oscillate back and forth in response to the alternating electric field.
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I asked my instructor that question once and he said about half the speed of light. We were talking about transmitting digital data but it's still electrical impulses. Hope that helps.