PHYS 1420 1st Edition Exam # 4 Study Guide Chapter 26 Index of refraction- the change in speed as a ray of light goes from one material to another causes the ray to deviate from its incident direction. n= index of refraction c= speed of light v=speed n=c/v is the ratio of speed of light in a vacuum to speed of light in the material n= 1 for a vacuum, Reflected and refracted rays Snell’s law Law of refraction- incident, reflected, refracted, and normal ray lie on the same planeθ 1 = is angle of incidence θ 2 = is angle of refraction Apparent depthd’ = apparent depth (height)d’= d (n2/n1)n1 and n2 are refractive indices Apparent height d’ = (n2/n1)d The internal reflection Sinθc = n2/n1 Occurs when light refracted into a medium has a lower index of refraction Refraction into medium Light may refract into a material where its speed is lower Angle of refraction is less than angle of incidence Refraction into mediumLight may refract into a material where its speed is higher. Angle of refraction is greater than angle of incidence Critical angle Is angle of incidence that results in angle of refraction of 90°Thin lens and magnification equationThe human eye-light enters cornea -iris controls lightRefractive power = 1/ f (in meters) Chapter 27Young’s double-slit experiment -light from 2 slits forms a pattern on screen -pattern is series of bright and dark parallel bands Constructive interference: bright fringe occurs Destructive interference: dark fringe occursThin film interference Diffraction Divergence of light from its initial line of travel is called diffractionOccurs when light of wavelength comparable to or larger than width of a slit Resolution Diffraction gratings Consist of a large number of equally spaced parallel
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