A prism creates a spectrum of colors from white light through a process known as dispersion. When white light, which is a combination of all visible colors, enters a prism, it slows down and bends, or refracts, as it passes through the prism. The amount of bending or refraction that occurs depends on the wavelength of each color in the white light.
Different colors of light have different wavelengths. Red light has the longest wavelength, while violet light has the shortest wavelength, with other colors like orange, yellow, green, blue, and indigo falling in between.
As white light enters the prism, it undergoes refraction and gets separated into its component colors because each color bends at a slightly different angle. This occurs because the speed of light changes when it enters a medium, such as a prism, which has a different refractive index than air.
The prism has a triangular shape with two angled faces and a base. The two angled faces of the prism act as surfaces of different refractive indices. When light enters the prism, it slows down and bends towards the base of the prism. The degree of bending depends on the wavelength of the light. Red light, having the longest wavelength, bends the least, while violet light, with the shortest wavelength, bends the most. The other colors bend at intermediate angles.
As a result, when the white light passes through the prism, it spreads out into a band of colors called a spectrum. The spectrum starts with red on one end, followed by orange, yellow, green, blue, indigo, and violet on the other end.
This phenomenon is known as dispersion, and it is the basis for how prisms create rainbows, as raindrops can act similarly to prisms, separating sunlight into its component colors. The spectrum of colors created by a prism is a representation of the different wavelengths present in white light, allowing us to observe the individual colors that make up the visible spectrum.