ASTR 106 Lecture Notes - Lecture 4: Electromagnetic Spectrum, Kinetic Energy, Thermal Energy
Document Summary
Light is complicated-its been understood as sa wave, a particle, a ray, and an object that sometimes acts like a wave and sometimes like a particle. Ole romer- studied movement of the moons of jupiter. Modern measurements of the speed of light: 3 x 10^8 m/s. Light travels that speed only in a vacuum-the speed of light through a medium such as air or glass is less than c. Energy: the ability to do work, comes in many forms. Thermal energy: sum of all the kinetic energy of the moving bits of matter inside a substance. Waves characterized by 4 quantities: amplitude, speed, frequency, and wavelength. Amplitude: height of the wave above the undisturbed position. Wavelength: distance from one crest of a wave to the next. Frequency: number of wave crests passing a point in space each second. Particle model: light is made up of massless particles called photons. Light energy is quantized: something subdivided into individual units.
