What is the primary function of a prism in optics?

A prism primarily serves to split light into its component colors through the process of dispersion. When light passes through a prism, it slows down and bends at different angles depending on its wavelength. This bending occurs because of the refractive index of the material of the prism, which varies for different wavelengths of light. As a result, a beam of white light separates into a spectrum of colors, typically red, orange, yellow, green, blue, indigo, and violet, vividly demonstrating the concept of dispersion.

This property is fundamental in various applications, including spectroscopy, where analyzing the spectrum of light allows scientists to understand material compositions, and in creating effects such as rainbows. The other options describe functions that do not accurately represent the primary role of a prism in optics. While focusing light or increasing brightness may be qualities of different optical systems, they are not the defining characteristics of a prism, which is specifically designed to disperse light. Similarly, absorbing light to reduce glare pertains to materials or filters rather than the function of a prism.