Producing visible light from a radio wave transmitter: why is it not possible? If it is, what are the limitations?

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    $\begingroup$ Why can't we? physics.umd.edu/deptinfo/facilities/lecdem/services/QOTW/arch13/… and on this page flateh.narod.ru/145mhz.htm demonstrated with a 145MHz transceiver and a fluorescent light. $\endgroup$
    – CuriousOne
    Dec 23 '14 at 16:51
  • $\begingroup$ I loved that demo in my intro physics class. Will always remember it. $\endgroup$
    – BMS
    Dec 23 '14 at 16:54
  • $\begingroup$ The link I've suggested is actually about the reverse process i.e. light inducing an oscillating current, but the physics is the same. It's because the frequency of visible light is at or above the plasma frequency of the metal aerial. $\endgroup$ Dec 23 '14 at 16:55
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    $\begingroup$ Actually Radio antenna producing waves in the visible spectrum would be a better duplicate, but the SE won't let me go back and change a duplicate link. $\endgroup$ Dec 23 '14 at 16:57
  • $\begingroup$ @JohnRennie: That's a very good answer on that previous question. It seems that the plasma frequency of metals can be adjusted by patterning into meta-materials (seems plausible enough), so the experimental realization of antenna structures for visible light may not be out of our reach for long. $\endgroup$
    – CuriousOne
    Dec 23 '14 at 17:07

Radio antennas generate electromagnetic fields. Light is a physical particle of energy called a photon. Since the the radio antenna doesn't generate particles of energy, no matter the frequency, it can't produce light. The flow of current in a conductor generates an electromagnetic field that propagates from the conductor. The generating of photons from an electric current is a different process and is on the atomic level. The electric current releases energy (photons) from individual atoms. Probably the most commonly know application of this process is the light emitting diode (LED). Until the scientific community admits that light, in fact, isn't part of the electromagnetic frequency spectrum, since light has no electric or magnetic properties, these confusions will continue.

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    $\begingroup$ This is simply wrong. All electromagnetic radiation, whether radio waves or visible light can be treated either as a wave or a particle i.e. photon. The difference is only in the energy of the photon. You're also wrong that current can't generate light directly as this is exactly how synchotron radiation is generated. It just can't be done in a metal wire. $\endgroup$ Dec 23 '14 at 17:59
  • $\begingroup$ Last things first. Current in a wire can generate photons, that's how an incandescent light bulb works. I just isn't electromagnetic. The synchrotron does generate photons. It appears when the super accelerated charged particles gain enough energy they produce a photon which having no magnetic property are no longer held by the super magnet and fly off to be seen as light. This supports that light is not electromagnetic. Thank you for pointing out a rare process for generating photons. $\endgroup$
    – Pappy3G
    Dec 24 '14 at 22:03
  • $\begingroup$ Would producing light in the visibl spectrum degrade the quality of antennas ? Wearing out ? $\endgroup$ Nov 7 '15 at 17:51

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