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# 2: Reflection and Transmission at Boundaries and the Fresnel Equations

When a ray of light encounters an interface between two media of different refractive indices, some of it is reflected and some is transmitted. This chapter will concern itself with how much is reflected and how much is transmitted. (Unless the media are completely transparent, some of the light will also be absorbed - and presumably degraded as heat - but this chapter will concern itself only with what happens at the interface, and not in its passage through either medium.) We shall do this at three levels: Normal incidence; incidence at the Brewster angle (we’ll explain what is meant by this); incidence at an arbitrary angle.

Thumbnail: Reflection at a surface. (Public Domain; Benbuchler).