A prism generates a spectrum of colors through the processes of refraction and dispersion of light.

When a beam of white light enters a prism, it undergoes refraction, or bending, at both the entrance and exit surfaces of the prism. This bending occurs because the speed of light changes as it transitions from one medium (air) to another (glass). Importantly, not all colors of light are refracted equally; each color, corresponding to a specific wavelength, travels at a slightly different speed within the glass of the prism. This variation in speed among different wavelengths is known as dispersion.

The dispersion of light into its individual colors results in the formation of a spectrum. Shorter wavelengths, such as blue and violet light, are refracted more significantly, while longer wavelengths, like red light, are refracted less. Consequently, the colors spread out to form a continuum, with violet appearing at one end and red at the other.

To further comprehend the phenomenon of dispersion, we can examine the refractive index of the prism material. The refractive index quantifies the extent to which a material can bend light. It varies with the wavelength of the light; shorter wavelengths experience greater slowing and are therefore associated with a higher refractive index. This variation in refractive index among different wavelengths is what causes dispersion and leads to the creation of a spectrum.

In summary, a prism produces a spectrum of colors by refracting and dispersing light. Each color, characterized by its unique wavelength, is refracted to a different degree due to its varying speed in the glass. This separation of colors, ranging from red to violet, manifests as a visible spectrum.