![]() ![]() ![]() Radio wavelengths are often measured in centimeters: 1 centimeter = 10 -2 meter = 0.01 meter. Visible light is sometimes also measured in nanometers(nm): 1 nanometer = 10 -9 meter = 10 Ångstroms, so in nanometers, the visible band is from 400 to 800 nanometers. Visible light (what your eye detects) has wavelengths 4000-8000 Ångstroms. A wavelength of light is defined similarly to that of water waves-distance between crests or between troughs.(Microwaves are high-energy radio waves.) From highest energy to lowest energy the forms of light are Gamma rays, X-rays, Ultraviolet, Visible, Infrared, Radio. All forms of light have the same speed of 299,800 kilometers/second in space (often abbreviated as c). The speed of light is constant in space.Other types of waves need some sort of medium to move through: water waves need liquid water and sound waves need some gas, liquid, or solid material to be heard. There are some general properties shared by all forms of electromagnetic radiation: The photons with the highest energy correspond to the shortest wavelengths. Scientists have observed that electromagnetic radiation has a dual "personality." Besides acting like waves, it acts like a stream of particles (called "photons") that have no mass. They travel through empty space as well as through air and other substances. These waves are also called "electromagnetic radiation" because they radiate from the electrically charged particles. Electromagnetic RadiationĮlectromagnetic waves are produced by the motion of electrically charged particles. In this lecture we Introduce the concepts of electromagnetic radiation, wavelength, frequency and the Photoelectric Effect. The content that follows is the substance of General Chemistry Lecture 24. ![]()
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