Monday, 1 June 2015

electricity - Why doesn't alternating current produce light while a vibrating single particle with a charge will


If a vibrating atom can produce light why can't an alternating current of electrons do the same?


EDIT: When I use the term "light" I mean all EMR



Answer



Yes, alternating current will radiate electromagnetic waves. For example, in telecommunication, the transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the antenna radiates radio waves.


The usual "pick up" that we get from electric currents in the circuits in the walls of a building have a frequency of about one hundred cycles per second. If we increase the frequency to $500$ or $1000$ kilocycles ($1$ kilocycles = $1000$ cycles) per second, we are
"on the air", for this is the frequency range which is used for radio broadcasts. (of course it has nothing to do with the air! we can have radio broadcasts without any air.)$^{*}$





$*$Extracted from the Feynman's lectures on Physics-Volume one.


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