When light passes through a prism, it undergoes a process called refraction. Refraction is the bending of light as it travels from one medium to another, such as from air to glass or from air to water. The amount of bending depends on the change in speed of light as it passes through the different medium.
When white light, which is composed of a range of colors with different wavelengths, enters a prism, it gets separated into its constituent colors. This separation is due to the phenomenon known as dispersion. Dispersion occurs because different colors of light have different wavelengths and hence different speeds in the prism. The longer wavelengths (such as red) are refracted less than the shorter wavelengths (such as violet), resulting in the spreading out of the colors.
The definition of wavelength of light refers to the distance between two successive peaks or troughs of a wave of light. Light is an electromagnetic wave, and the wavelength is one of its fundamental characteristics. It is typically denoted by the symbol λ (lambda) and is measured in units such as meters (m), nanometers (nm), or angstroms (Å). In the context of visible light, different colors have different wavelengths. For example, red light has a longer wavelength (around 700 nm), while violet light has a shorter wavelength (around 400 nm).