When light passes through a prism, several phenomena occur due to the change in medium from air to glass and back to air:
- Refraction : As light enters the prism from air (a less dense medium) into glass (a denser medium), it slows down and bends toward the normal line perpendicular to the surface. When it exits the prism back into air, it speeds up and bends away from the normal. This bending of light at the surfaces of the prism is called refraction
- Dispersion : White light is composed of multiple colors, each with a different wavelength. The prism's material has a refractive index that varies with wavelength, causing different colors to bend by different amounts. Shorter wavelengths (like violet and blue) bend more, while longer wavelengths (like red) bend less. This separation of white light into its constituent colors is called dispersion, producing a spectrum similar to a rainbow (red, orange, yellow, green, blue, indigo, violet)
- Emergence of spectrum : Because each color exits the prism at a different angle, the observer sees the white light split into a spread of colors. The angle between the original incident ray and the emerging ray is called the angle of deviation, which varies with wavelength
In summary, as light passes through a prism, it is refracted twice and dispersed into its component colors due to wavelength-dependent bending, resulting in a visible spectrum of colors emerging from the prism. This phenomenon illustrates the composite nature of white light and the wavelength dependence of refractive index in the prism material
