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Physics, Astronomy & Cosmology / Re: How does light speed up when it exits a denser material?
« on: 25/06/2015 14:25:30 »And interestingly, if an infra-red photon passed through the translucent material would it be visible on its passage as ‘red light’?
No, the frequency determines the "color," and that does not change from medium to medium. The wavelength must change, but ultimately it is the frequency (energy) that registers as the color in our eye.
If you consider the eye as the detector, then it doesn't matter what material the light passes through, ultimately the refractive index of the eye where the light is absorbed determines the "observed wavelength", but we can design an experiment to probe the color of light in other materials:
Say we have two solutions that each contain the same concentration of a dye that absorbs at a very specific frequency, but the two solutions also contain different amounts of some other dissolved species that changes the refractive index substantially (many additives could allow us to tune the refractive index by 10-20%, without changing the behavior of the dye). If the spectrum of light coming out of the solution is independent of the refractive index, that proves that the frequency determines color, not the wavelength (and if the absorbed light shifts with refractive index, that proves the wavelength is the important factor)