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Out of the 7 colours of the rainbow, violet has the highest frequency and the smallest wavelength. Does this mean that our eye sees it first? If yes, then why? Does it travel at the same or higher speed than other colours? Does the answer to that depend on the medium of propagation? Does the higher frequency decrease detection times, both in our eyes and on camera CCDs and the like?

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  • $\begingroup$ Is this a question of the response of the eye--- which colors excite the photoreceptors first? This depends on the intensity. The photoreceptors are molecular, and different molecules have different reaction times that depend on their structure and what they are attached to, rather than on the exciting photon energy. $\endgroup$
    – Ron Maimon
    Jun 20, 2012 at 19:33
  • $\begingroup$ This should be Migrated to Biology.SE, if it exists. I think it does exists. $\endgroup$
    – Abhimanyu Pallavi Sudhir
    Jun 6, 2013 at 13:41

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No, the speed of light is the same for all frequencies. The reason prisms work is because the deviation angle through the material depends on the frequency.

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  • $\begingroup$ What about the physiological response time as a function of wavelength? $\endgroup$
    – Alexey Bobrick
    Jun 20, 2012 at 12:31
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    $\begingroup$ Isn't the index of refraction precisely the ratio of wave (phase) velocity to velocity in the vacuum? $\endgroup$
    – Emilio Pisanty
    Jun 20, 2012 at 17:19
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Nothing like that, all colors (or in physics term, electromagnetic waves of any frequency) travels with the same speed which is denoted popularly by $c$, well the only difference is the scattering in a media. Scattering is inversely proportional to the wavelength, $\Rightarrow$ red scatters less as compared to blue or violet. Therefore red is usually preferred in places where the information is to be sent to a great distance, like the stop signal in traffic. That also explains why the sky appears blue rather than red. So in a way from a distance it is most likely to see red than blue rather than seeing red earlier than blue.

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    $\begingroup$ -1 everything after the first sentence is baloney. Light scattering has nothing to with why stop signals are red. $\endgroup$
    – user2963
    Jun 20, 2012 at 17:32
  • $\begingroup$ @zephyr: Check this out bro ...newton.dep.anl.gov/askasci/gen99/gen99420.htm $\endgroup$
    – Jaswin
    Jun 20, 2012 at 18:39

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