Refraction of Light: Why Frequency Stays Unchanged

[SandeshPhy]

Why does the frequency of light wave doesn't change during refraction ?

 

[zhermes]

Conservation of energy: the frequency of light is linearly related to its energy, thus if the frequency changed - so would its energy, and conservation of energy would be violated. Therefore, the frequency must stay constant.

 

[cupid.callin]

but the speed of light charges when it goes from one medium to another ... right?

 

[zhermes]

but the speed of light charges when it goes from one medium to another ... right?

Yes, absolutely---this is required so that the wavelength can change *without* the frequency changing.

I.e.
$$v = \lambda \nu$$ (velocity = wavelength * frequency)
$$E = h \nu$$ (Energy = Planck's constant * frequency = constant)