Dispersion contributes to the separation of white light into its component colors by taking advantage of the fact that different wavelengths of light bend by different amounts when passing through a medium like glass or water.
How Dispersion Causes Separation:
- White Light is a Mixture:
White light contains a combination of all visible wavelengths — red, orange, yellow, green, blue, indigo, and violet. - Entry into a Medium:
When white light enters a material like a glass prism or water droplet, it slows down and bends due to refraction. - Wavelength-Dependent Refraction:
- Shorter wavelengths (like violet and blue) bend more because they experience a higher refractive index.
- Longer wavelengths (like red) bend less because their refractive index is lower.
This unequal bending is what we call dispersion.
- Path Separation:
Since each color takes a slightly different path due to different bending angles, the light spreads out into a spectrum rather than remaining a single beam. - Visible Spectrum Emerges:
The result is the formation of a band of colors, typically seen as a rainbow or spectrum: red to violet.
Thus, dispersion is the key physical process that causes white light to split into its various colors, based on how each wavelength refracts differently in a medium.