On Vision and Colors from a prism, however, the production of white can be demonstrated by using a mixture of colored light from each of the three main pairs of complementary colors: red – green, orange – blue, or yellow – violet. White can be produced from two complementary opposite colors when both of the external causes of the colors excite the same retinal place at the same time. Newton claimed that white could be produced by the aggregation of his seven prismatic colors. He erroneously considered color to be in light instead of in the eye. White is the result of the combination
Spectrum with its own brightness or intensity. A rainbow, or prism, sends these component colors in different directions, making them individually visible at different angles. A graph of the intensity plotted against the frequency (showing the brightness of each color) is the frequency spectrum of the light. When all the visible frequencies are present equally, the perceived color of the light is white, and the spectrum is a flat line. Therefore, flat-line spectra in general are often referred to as "white", whether they represent light or another type of wave phenomenon (sound, for example, or vibration in a structure). In radio