# Refraction of Light

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

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.

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

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)