When sunlight passes through a prism, it disperses into a spectrum of colours. This demonstrates that sunlight is composed of all the colours of the visible spectrum. As different wavelengths of light are refracted (bent) to varying degrees as they pass through the prism, the light separates into component colours.

The colours of the spectrum range from red, orange, yellow, green, blue, indigo, to violet. This sequence is often remembered by the acronym ROY G. BIV. Each colour corresponds to a specific wavelength, with red having the longest wavelength and violet having the shortest.

This phenomenon of dispersion demonstrates the concept of refraction and helps understand the composition of light. It played a significant role in Isaac Newton's groundbreaking experiments on optics in the 17th century, contributing to the field of optics and laying the groundwork for many scientific discoveries.