This is a conceptual question. I already know the law of refraction but I need something like an idea of the Physical process from both particle and wave theory standpoints.
Why does a ray of light start changing its path at the boundary of two media of different optical densities? Why no deviation occurs at normal incidence? How do you visualize the bending happening?
Here is how I would visualize it. As the particles of light hit the boundary, the light scatters slightly. The scattering begins along the surface of the boundary, so that the surface of boundary creates a pattern of light. That is why the wavelength changes, its a side effect of being absorbed and re-emitted. Note that its really refraction, of course, not scattering, but I believe the principles are the same.
