According to Feynman, photons are not like little rubber balls that bounce off of the front surface of some material like glass, instead they are absorbed inside the material and a new photon is emitted.
Since a photon enters some distance into the material before being absorbed this should allow for an illustration using three normals. This will show the ratios of the different distances involved.
The shorter the distance c-a, the greater the probability for reflection. As the length c-a nears the same length of x1 and x2 the probability changes from reflection to refraction.
Set the distance b-a to 1 then compare the proportionalities of the other distances.
Some drawings:
http://imgbox.com/gallery/edit/XDbLx9QwZs
Since a photon enters some distance into the material before being absorbed this should allow for an illustration using three normals. This will show the ratios of the different distances involved.
The shorter the distance c-a, the greater the probability for reflection. As the length c-a nears the same length of x1 and x2 the probability changes from reflection to refraction.
Set the distance b-a to 1 then compare the proportionalities of the other distances.
Some drawings:
http://imgbox.com/gallery/edit/XDbLx9QwZs