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Maxwell2D: Sharp change in refractive index

Dielectric constant distribution

A sharp change in refractive index results in specular reflection from the surface and refraction into the medium according to Snell's law, with a reduction of the wave speed. The animation shows two panels: the left shows the complete wave field, while the right shows just the component that is scattered (calculated simply by subtracting the equivalent field in a vacuum). The bending of the light explains why the bottom of a pool of water appears is nearer than it really is. This kind of reflection is occasionally seen by clear-air radars as Fresnel scattering from sharp horizontal gradients in atmospheric refractive index.
Wikipedia link: Snell's law

Electric field animation

This is an animation of the component of the electric field out of the plane of the page.

Total field (incident plus scattered)       |      Scattered field (total minus incident)

Average Poynting vector

The direction in which energy is travelling at any instant is proportional to the cross product of the electric and magnetic fields, known as the Poynting vector. The arrows show the direction of the Poynting vector averaged over the simulation, while the colours show its strength.

Total field (incident plus scattered)       |      Scattered field (total minus incident)