Objectives: To study the principles of geometric optics: reflection, refraction. To become familiar and utilize Snell's Law. Materials: https://phet.colorado.edu/en/simulation/bending-light Theory: Principles of geometric optics: 1. The incident, reflected, and refracted rays, and the normal to the surface, all lie in the same plane. 2. The angle of reflection, 0,, is equal to the angle of incidence, 0; for all wavelengths and for any pair of substances. 3. When a light ray crosses the interface between two substances having different indices of refraction, the trajectory of the ray changes abruptly at the interface. The precise manner in which the direction of the ray changes is determined by a mathematical relationship known as Snell's Law. Snell's Law: Substance a Substance b Incident Da Normal Ob Refracted Reflected nasinba = nosing b where na and no are the indices of refraction for substance a and b respectively. Adobe 20 o- 30 DIL DD CA F6 co F10 F11 # 2 4 5 8 9 Q W E R T Y U O P A S D F G H Knasinla = nisinob where na and no are the indices of refraction for substance a and b respectively. Notes on Snell's Law: The bending of the ray is always such that the angle on the side with the higher index of refraction is the smaller one. The angles are with respect to the normal to the interface. . If the ray intersects the interface at a right angle (0a = 0), then there is no bending. Index of Refraction: The index of refraction of an optical material, denoted by n, is the ratio of the speed of light in vacuum (c) to the speed of light in the material (v): n = - Total Internal Reflection: When a ray traveling in a material a with an index of refraction na reaches an interface with a material b having index no where no