Cool Speed Of Light In A Transparent Material Fo Ideas. What is the index of refraction of the material? Web the speed of light in a vacuum is 299,792,458 metres/ second (though it is less in a transparent medium such as air, water or glass, depending on the refraction index).
Web for light with frequency f traveling in a transparent medium we have v = λ n f. A transition to a denser medium will result of a slow down of the propagation. When the index of refraction changes, the wavelength of the light changes, while the frequency f stays the same.
