Why do prisms split white light into a spectrum?

Prisms split white light into a spectrum due to a process called dispersion.

Dispersion is a phenomenon that occurs when light passes through a prism. White light is composed of different colours, each having a unique wavelength. When white light enters a prism, it slows down and bends, a process known as refraction. However, each colour bends at a slightly different angle due to their different wavelengths, causing them to spread out and separate into a spectrum of colours. This is why we see a rainbow of colours - red, orange, yellow, green, blue, indigo, and violet - emerging from the other side of the prism.

The order of the colours is determined by the wavelength of each colour. Red light has the longest wavelength and bends the least, while violet light has the shortest wavelength and bends the most. This is why red is always on the top of the spectrum and violet at the bottom when light is dispersed by a prism.

The concept of dispersion is a fundamental aspect of optics, the branch of physics that studies the behaviour and properties of light. It helps us understand not only why prisms can split white light into a spectrum, but also why we see rainbows after a rain shower. When sunlight hits raindrops, they act like tiny prisms, dispersing the light and creating a beautiful spectrum of colours in the sky.

In conclusion, the splitting of white light into a spectrum by a prism is a fascinating demonstration of the properties of light and the phenomenon of dispersion. It's a perfect example of how physics can help us understand and appreciate the world around us.