When light passes through a prism, it is separated into its various wavelengths. The "white" light from the sun is a collection of light of all wavelengths and is called Our sun is probably the most familiar example of a heated body giving off light. When an object is heated, it radiates energy, often in the form of visible light. Ultraviolet light, X rays, and gamma rays - all of which have wavelengths shorter and energies higher than those of visible light (see Figure 5.2) - are also invisible forms of radiant energy. The visible range has been expanded to show the individual colors. Infrared light, microwaves, television waves, and radio waves are invisible forms of electromagnetic radiation their wavelengths are greater than that of visible light, and thus their energies are lower than that of visible light.įIGURE 5.2 The electromagnetic spectrum. Red light, then, has a lower frequency and is associated with less energy than blue light. In Figure 5.2 you can see that red light has a longer wavelength than blue light. Notice thatĮlectromagnetic radiation with wavelengths between 4 X 10 -7 and 7 X 10 -7 m, comprises only one small part of the electromagnetic spectrum. The common names of the other kinds of electromagnetic radiation and their wavelengths are also given. Hence, the higher the frequency, the shorter the wavelength and the higher the energy of the wave.įigure 5.2 shows the wide range of electromagnetic radiation from AM radio waves with a wavelength of 10 4 m to gamma waves with a wavelength of 10 -12 m. The energy associated with a wave is directly proportional to its frequency. From this equation you can see that as wavelength increases, theįrequency of the wave decreases. Where c is the constant speed of light, 3.0 X 10 8 m/sec. (nu) of a wave is related to its wavelength Three waves of different wavelength are shown in Figure 5.1.įIGURE 5.1 Different waves have different wavelengths (distance from crest to crest).Ī wave can also be characterized by its frequency - that is, the number of wave crests that pass a given point in a unit time. (lambda), which is the distance from crest to crest.
The difference between these two types of waves is in their You may also have seen, on larger bodies of water like the ocean, waves that are farther apart. You have probably seen closely spaced, choppy waves on a small lake. In many ways the waves of electromagnetic radiation are like waves in water. Travels through a vacuum in waves at a constant speed of 3.0 X 10 8 m/sec. Radiant energy, also known as electromagnetic radiation, To some extent, the properties of electrons can be compared with the properties of a closely related phenomenon, radiant energy or light.
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