I know the wavelength is distance between 2 point of maximum sine wave. when the conductor length is very shorter than wavelength, what is meaning of wavelength? ??(how long distance propagate in short length? ??)


The wavelength of the signal doesn't depend on the length of the conductor it's transmitted over. You could say, it's the distance that would be between two maxima if the line was long enough to contain the full wavelength. If the conductor is short you may not be able to measure the wavelength directly, but you can, for example, measure the frequency and determine the wavelength from that.

On the other hand, if the conductor (transmission line) is much shorter than the wavelength of the signal, then distributed circuit effects are likely to be insignificant anyway, so the wavelength of the signal will likely not matter to the circuit's operation. For more clarification on this point, see this recent question.

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  • \$\begingroup\$ Thank you.But the wavelength means didistance traveld by electron charge or distance between electron charge? \$\endgroup\$ – linuscomex Jul 7 '15 at 11:20
  • \$\begingroup\$ It's the distance between similar points on a wave. In the case of transmission lines, it could be either the voltage or current wave (the wavelength will be the same, whichever way you measure). I suppose it could also be the charge density wave, but afaik there's no benefit to thinking of it that way, since the governing equations for transmission lines are in terms of voltage and current. \$\endgroup\$ – The Photon Jul 7 '15 at 15:45
  • \$\begingroup\$ I know its not benefit but I want to know how current that have 1 kilometer wavelength make full cycle in 10 cm conductor ? \$\endgroup\$ – linuscomex Jul 8 '15 at 18:32
  • \$\begingroup\$ If wavelength is distance traveled by electron charge in one cycle of wave so it possible. \$\endgroup\$ – linuscomex Jul 8 '15 at 18:34
  • \$\begingroup\$ @linscomex, Individual electrons don't need to travel the length of the conductor for there to be a current. Also the velocity of any individual electron is much slower than the propagation velocity of a wave along a transmission line. You don't need to worry about the distance traveled by an electron any more than you need to worry about the distance travelled by an air molecule when you hear someone talking from across the room. \$\endgroup\$ – The Photon Jul 8 '15 at 18:45

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