(a) Away from the normal
We can find the direction of bending of the ray of light by using Snell's equation:
where we have:
n1, n2: index of refraction of the first and second medium
; angle that the incident and the refracted ray form with the normal to the surface
Here, the light ray moves from a material with high index of refraction to a material with lower index, so we have
Re-arranging Snell's law we find
since we have
this implies
so the ray of light bends away from the normal.
(b) The wavelength is greater in the second material (the one with lower index of refraction)
The wavelength of the light in a medium is given by
where
is the wavelength of the light in a vacuum
n is the refractive index
The equation can be rewritten as
and again it can be rewritten as
where
Therefore, we have that the wavelength in the second medium (the one with lower index of refraction) is longer than the wavelength in the first medium.
(c) The frequency remains the same
Wavelength and speed of a light ray depend on the medium in which the wave is travelling through, however the frequency does not depend on that, so it remains the same in the two mediums.
