Topic 1: Introduction to Dispersion of Light

Dispersion of Light

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

White Light

White light is a mixture of different colours. Each colour has a different wavelength.

Spectrum

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

Colours of Spectrum

The seven colours obtained are:

  • Violet
  • Indigo
  • Blue
  • Green
  • Yellow
  • Orange
  • Red

(Mnemonic: VIBGYOR)

Cause of Dispersion

Dispersion occurs because different colours of light travel with different speeds in a medium.

Examples of Dispersion

  • Rainbow formation
  • Splitting of light through a glass prism

Importance of Dispersion

  • Explains formation of rainbow
  • Helps understand nature of white light
  • Frequently asked conceptual topic in MHT-CET
Q1. Dispersion of light is the phenomenon of:
A) Reflection of light
B) Refraction of light
C) Splitting of white light into colours
D) Bending of light only

Answer: C


Q2. The band of colours obtained due to dispersion is called:
A) Image
B) Ray
C) Spectrum
D) Beam

Answer: C


Q3. Which of the following shows dispersion of light?
A) Plane mirror
B) Glass slab
C) Prism
D) Lens

Answer: C


Q4. The correct order of colours in spectrum is:
A) RYGBIVO
B) VIBGYOR
C) RGBVIOY
D) YORGBIV

Answer: B


Q5. Dispersion occurs because:
A) Light travels in straight line
B) All colours have same speed
C) Different colours have different speeds
D) Light reflects inside prism

Answer: C

Chapter 14: Dispersion of Light

Topic 1: Introduction – Quick Revision

1. Dispersion

Splitting of white light into its constituent colours.

2. Spectrum

Band of colours obtained after dispersion.

3. Colours of Spectrum

VIBGYOR

4. Cause

Different colours travel with different speeds in a medium.

Exam Focus (MHT-CET)

Direct MCQs are asked on definition, spectrum and order of colours.


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