Refraction Physics Department, New York City College of Technology

Key words Index of refraction Law of refraction Critical angle Total internal reflection Thin lens Thin lens equation Ray tracing

Index of refraction Definition c is the speed of light in free space v is the speed of light in a given material n is unitless

Law of refraction (Snell’s law) Snell’s law  1 is the angle of incidence  2 is the angle of refraction

Example #1 refraction

Total internal reflection Occurs when light passes from high index material to a low index material Critical angle  C For incident angles >  C, there is no refracted ray => total internal reflection

Total internal reflection Disc 22, #11

Optical path in fibers Disc 22, #14

Example #2 Total internal reflection

Thin lenses Converging lens Diverging lens

Ray tracing 3 special rays P ray F ray M ray

Ray tracing with lenses Disc 22, #18

Thin lens equation Magnification

Sign conventions f: + for converging lens,  for diverging lens. do: + if on the side of the lens from which the light is coming; otherwise,  di: + for a real image,  for a virtual image hi: + for upright image,  for inverted image

Example #3 Thin lens