Dispersion of light in a glass prism is the process by which white light splits into its component colors (spectrum) when it passes through the prism. This happens because the refractive index of glass varies with the wavelength of light, causing different colors to bend by different amounts.
Process of Dispersion in a Glass Prism:
- Refraction at the First Surface:
When white light enters the prism, it slows down and bends because glass is denser than air. This bending is called refraction. - Wavelength-Dependent Bending:
- Shorter wavelengths (like violet and blue) bend more.
- Longer wavelengths (like red) bend less.
This unequal bending is due to the variation of refractive index with wavelength — a phenomenon called chromatic dispersion.
- Internal Travel and Second Refraction:
Inside the prism, the separated colors travel at slightly different speeds. When they exit the prism, they bend again, spreading out even further. - Formation of Spectrum:
The final result is a visible spectrum of colors — red, orange, yellow, green, blue, indigo, and violet (ROYGBIV) — emerging from the other side of the prism.
So, dispersion in a glass prism occurs due to differences in refractive index for different wavelengths, causing white light to separate into its constituent colors.