Visible light is a complex phenomenon that is classically explained with a simple model based on propagating rays and wavefronts, a concept first proposed in the late 1600s by Dutch physicist Christiaan Huygens. Electromagnetic radiation, the larger family of wave-like phenomena to which visible light belongs (also known as radiant energy), is the primary vehicle transporting energy through the vast reaches of the universe. The mechanisms by which visible light is emitted or absorbed by substances, and how it predictably reacts under varying conditions as it travels through space and the atmosphere, form the basis of the existence of color in our universe.
Coined by Sir James Clerk Maxwell, the term electromagnetic radiation, is derived from the characteristic electric and magnetic properties common to all forms of this wave-like energy, as manifested by the generation of both electrical and magnetic oscillating fields as the waves propagate through space. Visible light represents only a small portion of the entire spectrum of electromagnetic radiation, which extends from high-frequency cosmic and gamma rays.
Explore this tutorial of an electromagnetic wave as a sine function which enables the visitor to vary amplitude and wavelength to demonstrate how this function appears in three dimensions.
Discover the relationship between frequency, wavelength, and energy, and enables the visitor to adjust the intensity of the radiation and to set the wave into motion in this interactive tutorial.
Examine how photon energy is absorbed by an electron to elevate it into a higher energy level and how the energy can be released, in the form of a lower energy photon, when the electron falls back to the original ground state.
Discover how electrons in fluorophores are excited from the ground state into higher electronic energy states and the events that occur as these excited molecules emit photons and fall back into lower energy states.
Examine and learn more about how a variable capacitor is coupled to a simple antenna transformer circuit to tune a radiofrequency spectrum in this featured interactive java tutorial.
Selected Literature References
The reference materials listed in this section are an excellent source of additional information on the diverse topic of electromagnetic radiation. Included are references to books, book chapters, and review articles, which discuss the theory and applications of electromagnetic radiation and how they relate to the physics of light and color.