FREQUENCIES AND COLOR

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1-27 FREQUENCIES AND WAVELENGTHS Compared to sound waves, the frequency of light waves is very high and the wavelength is very short. To measure these wavelengths more conveniently, a special unit of measure called an ANGSTROM UNIT, or more usually, an ANGSTROM (   ZDV GHYLVHG  \$QRWKHU FRPPRQ XQLW XVHG WR measure these waves is the millimicron (P      ZKLFK LV RQH PLOOLRQWK RI D PLOOLPHWHU  2QH P) HTXDOV WHQ angstroms. One angstrom equals 1055-10m. Q33.   What unit is used to measure the different wavelengths of light? FREQUENCIES AND COLOR For our discussion of light wave waves, we will use the millimicron measurement. The wavelength of a light determines the color of the light. Figure 1-18 indicates that light with a wavelength of 700 millimicrons is red, and that light with a wavelength of 500 millimicrons is blue-green. This illustration shows approximate wavelengths of the different colors in the visible spectrum. In actual fact, the color of light depends on its frequency, not its wavelength. However, light is measured in wavelengths. Figure 1-18.—Use of a prism to split white light into different colors. When the wavelength of 700 millimicrons is measured in a medium such as air, it produces the color red, but the same wave measured in a different medium will have a different wavelength. When red light which has been traveling in air enters glass, it loses speed. Its wavelength becomes shorter or compressed, but it continues to be red. This illustrates that the color of light depends on frequency and not on wavelength. The color scale in figure 1-18 is based on the wavelengths in air. When a beam of white light (sunlight) is passed through a PRISM, as shown in figure 1-18, it is refracted and dispersed (the phenomenon is known as DISPERSION) into its component wavelengths. Each of these wavelengths causes a different reaction of the eye, which sees the various colors that compose the visible spectrum. The visible spectrum is recorded as a mixture of red, orange, yellow, green, blue, indigo, and violet. White light results when the PRIMARIES (red, green, and blue) are mixed