AY 101 Lecture Notes - Lecture 7: Cosmic Microwave Background, Electromagnetic Spectrum, Electric Field
Document Summary
Electromagnetic forces bind electrons and atomic nuclei into atoms, atoms into molecules, and molecules into substances. Electromagnetism is the general term for the forces involved between charged particles. Our bodies are held together by electromagnetic forces. Random motions of charged particles disturb these fields. The disturbances are radiated away as waves of changing electric fields. Electric field waves induce magnetic field waves. Result: an electromagnet wave, which we perceive as light. As the wave propagates, the electric magnet fields vary in tandem. But there is only one speed: 670 million miles per hour in vacuum, independent of wavelength: vacuum is an empty space. Number of crests passing a given point every second. A particle of light that carries the energy of an electromagnetic wave. The shorter the wavelength, the higher the energy of a photon. Infrared rays: less energetic than red light, broken-up into short (near-ir, sensitive to cool stars), intermediate (mid-
