Topic 4: One-Page Revision Sheet

Chapter 14: Dispersion of Light – One Page Revision

1. Dispersion of Light

Dispersion is the phenomenon in which white light splits into its constituent colours when it passes through a transparent medium like a prism.

2. White Light

White light is a mixture of seven colours having different wavelengths.

3. Spectrum

The band of colours obtained after dispersion of white light is called a spectrum.

4. Colours of Spectrum

VIBGYOR
(Violet, Indigo, Blue, Green, Yellow, Orange, Red)

5. Cause of Dispersion

Different colours of light travel with different speeds in a medium and hence have different refractive indices.

6. Dispersion Through Prism

• A prism has two inclined refracting surfaces
• White light splits into seven colours
• Each colour deviates by a different amount

7. Deviation of Colours

• Violet light deviates the most
• Red light deviates the least

8. Scattering of Light

Scattering is the deviation of light from its straight path due to small particles present in a medium.

9. Tyndall Effect

Scattering of light by colloidal particles is called the Tyndall effect.

10. Wavelength Dependence of Scattering

• Shorter wavelength → more scattering (blue)
• Longer wavelength → less scattering (red)

11. Applications of Scattering

• Blue colour of the sky
• Reddish appearance of sun at sunrise and sunset
• Visibility of light beam in fog or smoke

12. Important CET Points

• Definition of dispersion and spectrum
• Order of colours (VIBGYOR)
• Maximum and minimum deviation colours
• Cause of dispersion
• Tyndall effect and its examples
• Blue sky and red sun explanation