Dispersion of light
- CBSE · NCERT Class 10, Ch 10 The Human Eye and the Colourful World
Dispersion is the splitting of white light into its separate colours, as when sunlight passes through a glass prism.
White light is a mix of colours. A glass prism bends each colour through a different angle, so the colours come out along different paths. The band of colours on a screen is called a spectrum.
The order is violet, indigo, blue, green, yellow, orange and red. The word VIBGYOR helps you remember it. Red bends the least and violet bends the most. A rainbow is the same effect: raindrops act like tiny prisms.
A small example
A narrow beam of sunlight falls on one face of a prism. On a screen you see 7 colours, from red at one end to violet at the other. Red has bent the least. Add a second prism, turned upside down. The colours join again and white light comes out.
Where marks go
Question 39 of CBSE's 2026-27 Science sample paper, option B, is on dispersion. Its scheme gives 1 mark for the definition and 1 for red as the least deviated colour. The labelled prism diagram carries 2 marks. The 2026-27 Science marking scheme gives the definition as splitting by refraction that depends on wavelength.
Keep dispersion apart from scattering. An assertion-reason question can give a reason that blames scattering for the spectrum. That reason is false: the colours come from dispersion.
Sources
Facts last checked against these sources on 30 September 2026.
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