The angle of deviation and dispersion in a prism are closely related, as both involve how light bends when passing through the prism. Here’s how they are connected:
1. Angle of Deviation:
- The angle of deviation is the angle between the incident ray (entering light) and the emergent ray (exiting light) after it passes through the prism.
- It measures how much the light path is bent (or deviated) by the prism.
2. Wavelength Dependence:
- The deviation angle depends on the wavelength of the light because different wavelengths experience different refractive indices.
- Shorter wavelengths (e.g., violet) bend more, resulting in a larger angle of deviation.
- Longer wavelengths (e.g., red) bend less, resulting in a smaller angle of deviation.
3. Relation to Dispersion:
- The difference in deviation angles between different colors is what causes dispersion.
- This difference is called angular dispersion — the angular separation between the deviated rays of different wavelengths.
4. More Dispersion = Greater Spread:
- A greater variation in deviation angles means more dispersion, producing a wider spectrum of colors.
- Prisms with materials having higher dispersive power (e.g., flint glass) show greater differences in deviation angles.
In summary, dispersion arises because the angle of deviation varies with wavelength — this variation spreads white light into a spectrum.