ASTR 170B1 Lecture Notes - Lecture 5: Photon, Wind Wave
28 Sep 2016
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Document Summary
Matter, light, and energy -- how we know about the universe. Basic premise: laws of physics apply everywhere in the universe. We can discover these laws from experiments on earth, and apply them to distant universe. Sound waves: pressure change in air, liquid or solid. Water waves (rocks thrown in a pond) The wave -- position of fans in a stadium. Frequency: number of crests passing a point wach second of time. Units: crest per second = 1 hertz (hz) Velocity of wave = wavelength x frequency. Velocity of light: same for all colors on air or a vacuum -- glass is different) Light waves are electric and magnetic disturbances moving through space pr some material (like glass) Meter is ok, but use nm (nanometers) So electrons feel forces from such waves. German physicist max planck in 1900 invented quantum theory to explain how light and atoms itneract. Energy of a photon depends on its wavelength (or frequency)
