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Question
How does the deviation produced by a triangular prism depend on the colours (or wavelengths) of light incident on it?
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Solution
The deviation caused by a prism increases with the decrease in the wavelength of light incident on it.
RELATED QUESTIONS
Name three factors on which the deviation produced by a prism depends and state how does it depend on the factors stated by you.
(i) Draw a diagram to show the splitting of white light by a prism into its constituent colour.
(ii) Draw another diagram to show how the colours of spectrum of white light can be combined
to give the effect of white light.
Fig shows part of the arrangement for obtaining pure spectrum.
(a) Complete thediagram and show how to obtain a pure spectrum.
(b) What are the conditions necessary for obtaining a pure spectrum?

Light of different colours is deviated through different angles by a prism. Explain the reason.
What is understood by the term dispersion of light? What is its cause?
Name the radiation of a wavelength longer than 8 × 10−7 m.
A prism causes dispersion of white light while a rectangular glass block does not. Explain.
Draw a neat diagram to show the arrangement you would use to project a pure spectrum of white light on a screen.
The wavelengths for the light of red and blue colours are nearly 7·8 × 10-7 m and 4·8 × 10-7 m respectively.
Which colour has greater speed in glass?
