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Physics

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  • $\begingroup$ The explanation given by Manishearth is excellent. However, the energy will change if you change frequency or wave length, since E=hn or E=hc/l where n and l are the frequency and wave length of light. How to explain this behavior along with the changes in wave length of light when light enter in to a medium? $\endgroup$ Commented Aug 8, 2012 at 17:00
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    $\begingroup$ @sst When the wavelength of light enters a medium, it slows down. Therefore the speed is not c anymore. The decrease in velocity is proportional to the decrease in the wavelength, which is how the Energy stays constant in the equation E=hc/l. $\endgroup$ Commented Dec 4, 2012 at 5:17
  • $\begingroup$ @Manishearth, you state: This means that the light wave is altered in some manner, but it's not clear why it's altered, what makes it altering. $\endgroup$ Commented Feb 5, 2013 at 7:33
  • $\begingroup$ "In this case, since λν=v, and ν is constant, change of speed requires change of wavelength." intuitely, so to say, okay, but not correct, Many related question/answers say that speed of light remains and must remain (intuitively: any velocity below c would hurt rest mass zero). Explanation ist: in certain media light travels longer paths. It is slowed down only virtually as it's got to travel longer routes. Colour, thus wavelenght, does not change. $\endgroup$ Commented Nov 18, 2022 at 13:27