Final answer:
A white light is produced by mixing all the visible wavelengths, which range from approximately 400 to 750 nanometers. This phenomenon, known as dispersion, is what causes the range of colors seen in a rainbow when white light is dispersed.
Step-by-step explanation:
A white light is formed when all the wavelengths of the visible spectrum are mixed. This includes the colors we see in a rainbow—red, orange, yellow, green, blue, and violet; sometimes indigo is included as well. When white light is passed through a prism or is observed in a rainbow, it is dispersed into these colors, forming a continuous spectrum. This process is known as dispersion, and it showcases that sunlight, which we generally perceive as white, contains all visible wavelengths. Our eyes are capable of differentiating thousands of hues based on the mixture of wavelengths that come into contact with the eye, understanding white light as a uniform blend of all visible wavelengths from about 400 to 750 nanometers.