What causes sunlight to separate into different wavelengths and display a rainbow of colors when passed through a prism?

The phenomenon where sunlight separates into different wavelengths and creates a rainbow of colors when it passes through a prism is primarily due to refraction. Refraction occurs when light travels from one medium to another medium with a different density, which changes the speed of the light as it enters the new medium.

In the case of a prism, when sunlight enters the prism, it slows down and bends. Each wavelength (color) of light bends at a slightly different angle because different wavelengths have different speeds in the prism material. This differential bending causes the various colors within the white light spectrum to spread out and become visible, creating a spectrum that includes red, orange, yellow, green, blue, indigo, and violet.

This understanding of refraction is crucial because it explains how prisms separate light into its component colors, unlike reflection, diffraction, or absorption, which involve different interactions of light with materials and do not lead to the same separation effect seen in a prism.