What causes the separation of colours in a prism?

The separation of colours in a prism is caused by a phenomenon known as dispersion.

Dispersion is a process where white light is separated into its constituent colours when it passes through a prism. This happens because different colours of light have different wavelengths, and these wavelengths are refracted, or bent, by different amounts as they pass through the prism.

White light, such as sunlight, is made up of a spectrum of colours, each with a different wavelength. When this light enters a prism, it slows down and bends, a process known as refraction. However, the degree to which the light bends depends on its wavelength. Shorter wavelengths (like blue and violet light) are refracted more than longer wavelengths (like red and orange light). This difference in refraction causes the light to spread out into a spectrum of colours, a process known as dispersion.

The result is a rainbow of colours, with red light refracted the least and therefore appearing at the top, and violet light refracted the most and appearing at the bottom. This is why we see a rainbow of colours when white light passes through a prism.

In summary, the separation of colours in a prism is caused by the dispersion of light. This is a result of the different degrees of refraction experienced by different wavelengths of light as they pass through the prism. This process transforms white light into a beautiful spectrum of colours, demonstrating the diverse nature of light.