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Visible light

Discussion in 'General Electronics Discussion' started by Jeanguypataterubberboot, May 24, 2018.

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  1. Jeanguypataterubberboot

    Jeanguypataterubberboot

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    If a transmitter transmits a signal at the frequency of visible light. Will the human eye see it at the antenna?

    Just curious.

    Pierre
     
  2. Bluejets

    Bluejets

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    Don't know about anyone else but I still have to use a multimeter to check dc.
    Looked at a lot of pcb's and never seen electricity yet.
     
  3. Harald Kapp

    Harald Kapp Moderator Moderator

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    Then it transmits light. You don't use antennas to transmit light, you use lenses or mirrors..
     
  4. Jeanguypataterubberboot

    Jeanguypataterubberboot

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    So what is the difference between a radio signal at light frequency and light at the same frequency?
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Nothing.
     
    Arouse1973 likes this.
  6. Harald Kapp

    Harald Kapp Moderator Moderator

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    A radio signal at light frequency is called light.
     
  7. Jeanguypataterubberboot

    Jeanguypataterubberboot

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    Jul 9, 2013
    So theoretically you should be able to see the antenna glow?
     
  8. Hopup

    Hopup

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    Just turn lamp on and see if it glows
     
  9. Ratch

    Ratch

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    There is no radio signal at light frequency. The components that make a radio are incapable of interacting with light and vice versa. A radio and lantern operate on far separate frequency ranges.

    Ratch
     
    davenn and Arouse1973 like this.
  10. KJ6EAD

    KJ6EAD

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    hevans1944 likes this.
  11. FuZZ1L0G1C

    FuZZ1L0G1C

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    From what I've read up previously (open to correction):
    Visible light is made up of photons.
    Photons travel in packets called 'quanta'.. (i think).
    They are unaffected by magnetic fields.
    A photon is a massless particle, with higher energy as frequency increases.
    The electron-volt energy ev is the energy that one photon posesses at a given frequency.
    The wavelength of light is from about 685 nm (red) to 380 nm (violet).
    That's a frequency of 442THZ red to 789THZ violet.
    As a nm is 1E-9 m or 1 millionth of a mm, components would be larger than the longest (red) wavelength.
    y Probably smaller than most molecules.
    Which is why electron scanning or tunneling microscopes are used for <1um viewing.
    So, no, ya cain't.
     
    Last edited: Jun 12, 2018
  12. AnalogKid

    AnalogKid

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    A single wavelength would be less than 1 um long, but an antenna could be any length you want, such as a (large) integral number of wavelengths.

    ak
     
  13. AnalogKid

    AnalogKid

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    Apples and oranges. In terms of the source of the visible light, thermal radiation from a DC-heated resistor is not the same as an RF oscillator connected to an antenna. His question is whether or not the results of the two would be the same.

    ak
     
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  14. Harald Kapp

    Harald Kapp Moderator Moderator

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    I doubt that for the same wavelength you could make a difference between the radiation. Maybe with some very sophisticated equipment by judging from the noise and harmonic content (as you may discern laser light from LED light by the difference in coherence). Only that a heated resistor will emit a broaad spectrum of light, not a "single" frequency.
     
  15. davenn

    davenn Moderator

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    Actually, AK response is pretty good

    You are not going to be transmitting RF at thermal frequencies
    Thermal freq's are IR ( Infra-red) RF is much lower
     
  16. davenn

    davenn Moderator

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    you use filaments in light globes, semi conductor interactions in LEDs to do the transmitting ….. lenses and mirrors just do focussing/reflecting they don't generate light
     
  17. Harald Kapp

    Harald Kapp Moderator Moderator

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    I agree I haven't been as precise as I should have been: I was thinking along the lines of beam forming or directional reception.
     
  18. Harald Kapp

    Harald Kapp Moderator Moderator

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    The op's question concerned
    RF,visible light, infrared etc. all are electromagnetic waves distinct by the wavelength (or freqency, whichever you prefer).
    The original question was not about thermal radiation. A laser, for example, can be considered an oscillator at the wavelength of visible light and would fit the op's question better.
     
  19. AnalogKid

    AnalogKid

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    I wasn't addressing differences in the radiation, only my interpretation of the OP's original question about the generation of the radiation. If you (or the crazies at NIST) build a sinewave oscillator circuit that oscillates at the frequency of green, will you see green?

    ak
     
    davenn likes this.
  20. Externet

    Externet

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    The transmitter that transmits a signal at the frequency of light, will be a PN junction like a LED or laser.
    The human eye will see the light emitted, but it is not called antenna, it is a light emitter.
     
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