TOC 1 Physics 212 and 222 Refraction and Lenses Refractive Index Snell’s Law Dispersion Rainbows Total Internal Reflection Apparent Depth

TOC 2 Physics 212 and 222 Refraction and Lenses Refractive Index The speed of light in a vacuum is The speed of light in other materials (media) is always slower. The index of refraction (refractive index) is the ratio of the speed of light in vacuum over the speed of light in the material. Refractive index is a property of the material.

TOC 3 Physics 212 and 222 Refraction and Lenses How does refractive index change the light? θ1θ1 θ2θ2

TOC 4 Physics 212 and 222 Refraction and Lenses n1n1 n2n2 θ 1 θ 1 ’ θ 2 Snell’s Law

TOC 5 Physics 212 and 222 Refraction and Lenses Dispersion Index of refraction is a function of wavelength. Longer wavelengths usually move faster in a medium.

TOC 6 Physics 212 and 222 Refraction and Lenses Rainbows Primary rainbows come from one reflection. Secondary rainbows come from two reflections © 1999 – 2002, HMI, Arbeitsgruppe Nukleare Messtechnik, Prof. W. von Oertzen

TOC 7 Physics 212 and 222 Refraction and Lenses n1n1 n2n2 θ1θ1 θ2θ2 90 o θcθc The critical angle for total internal reflection is θ 1 = θ c w hen θ 2 = 90 o.

TOC 8 Physics 212 and 222 Refraction and Lenses n1n1 n2n2 The apparent depth of the shark is given by as calculated by the equation d d’

TOC 9 Physics 212 and 222 Refraction and Lenses Refractive Index Snell’s Law Dispersion Rainbows Total Internal Reflection Apparent Depth