Physics 312 Lecture: "Dispersion and Total Internal Reflection" Apr 17, 1998

• The index of reflection of material changes with wavelength
  • Long wavelengths get refracted a little
  • Short wavelengths get refracted a lot
• One consequence is that light of different wavelengths is bent through different angles when it passes from one medium to another: dispersion
• When light of different wavelengths is spread out, the result is a spectrum
• When material is vaporized and heated, it absorbs and/or emits light of very specific wavelengths; each element has its unique set of wavelengths
• If light passes from a medium with high index of refraction to one with a low index of refraction, at a glancing angle, it may fail to pierce the interface: total internal reflection
• Total internal reflection occurs when

                   (n1 / n2) * sin(theta1) > 1
  

This lecture discusses material in Chapter 35 of Serway.

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