Is it possible to differentiate between two substances purely based upon how two mediums refract different colors of light?
It is clear that different elements absorb (and emit) light very differently at different wavelengths (Wikipedia: Absorption Spectrum). This is to my knowledge how astronomers identify the atmospheric composition of celestial bodies. Is there an analogous phenomenon for refraction?


1 Answer 1


Refractive index is not the same at every wavelength. In addition, it can vary due to environmental conditions such as temperature and pressure, and even light intensity. If the index is exactly the same for two materials at some wavelength, then their refraction behavior at that wavelength will be exactly the same. If two materials have the same index at some wavelength, it's extremely unlikely that they will have the same index at any other wavelength. So in principle it is possible to distinguish materials by the way the disperse different wavelengths. It's practically impossible for two different materials to have exactly the same index behavior at all wavelengths.

  • $\begingroup$ Thank you! that's perfect $\endgroup$
    – Jacob Wise
    Oct 11, 2019 at 20:00

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