ectromagnetic radiation. Maxwell, a nineteenth-century physicist, had a keen interest in electricity and magnetism. One of his major accomplishments was the development of mathematical equations that describe how electricity and magnetism work together to produce light and radio waves. He also developed a color triangle which is commonly used in art and physics classes to explain the relationship between the primary colors (red, blue, Understanding Light and green) to other colors. Later in this chapter we will examine the Maxwell color triangle. Work by Maxwell and other scientists showed that light could be categorized as a series of electromagnetic waves, with the human eye responding to different wavelengths, referred to as visible light, while ignoring other wavelengths. Basics of Electromagnetic Waves When the human eye views light as a series of electromagnetic waves, it becomes a relatively simple task to place this light in the frequency spec- trum and to discuss its ability to convey information. However, before we do this, let's describe and discuss the basic parameters of a wave: its frequency and wavelength. Frequency In a series of electromagnetic waves, represented as light, the waves oscil- late at different frequencies. Here the term frequency is used to refer to the number of periodic oscillations or waves that occur per unit time. Figure 2.2 illustrates two oscillating waves at different frequencies. The top portion of the figure illustrates a sine wave operating at one cycle per second (cps). Note that the term cycles per second in general has been replaced by the synonymous term hertz (Hz), after Heinrich Hertz, a famous German scientist known for his work in the field of electromag- netism during the latter part of the nineteenth century. The lower por- tion of Figure 2.2 shows the same sine wave after its oscillating rate has been doubled to 2 Hz. The time required for a signal to be transmitted over a distance of one wavelength is referred to as the period of the signal. The period rep- re