14.9 Dispersion of Light by Prism
A prism is an optical object typically made of glass with triangular and rectangular sides. It bends light passing through it due to refraction. Since visible light consists of a range of wavelengths, and refraction depends on wavelength, different wavelengths bend at different angles, causing dispersion.
lightbulbThe splitting of white light into its seven constituent colours when passing through a prism is called dispersion of light.
When white light enters a prism, it slows down and bends toward the normal. Each colour has a unique wavelength, and as light travels through the prism, each wavelength refracts at a different angle. Shorter wavelengths (violet, blue) bend more than longer wavelengths (red, orange). As a result, the light exiting the prism separates into seven distinct colours: red, orange, yellow, green, blue, indigo, and violet, forming the visible light spectrum.
Beyond the visible spectrum, prisms can also disperse infrared (IR) and ultraviolet (UV) light, though these wavelengths are invisible to the human eye. Special detection methods, such as infrared thermometers with sensors, are used to measure these wavelengths. This technology allows for non-contact temperature measurement, such as checking human body temperature.