Advertisements
Advertisements
Question
A prism causes dispersion of white light while a rectangular glass block does not. Explain.
Advertisements
Solution
In a prism, the refraction of light takes place at the two slant surfaces. The dispersion of white light occurs at the first surface of the prism where its constituent colours have deviated through different angles. At the second surface, these split colours suffer the only refraction and they get further separated. But in a rectangular glass block, the refraction of light takes place at the two parallel surfaces. At the first surface, although the white light splits into its constituent colours on refraction, these split colours on suffering refraction at the second surface emerge out in form of a parallel beam, which gives an impression of white light.
RELATED QUESTIONS
Why is the colour red used as a sign of danger?
Name three factors on which the deviation produced by a prism depends and state how does it depend on the factors stated by you.
How does the deviation produced by a triangular prism depend on the colours (or wavelengths) of light incident on it?
Which colour of white light travels fastest in glass?
In following figure shows a thin beam of white light from a source S striking on one face of a prism.
Complete the diagram to show effect of prism on the beam and to show what is seen on the screen.
Light of different colours is deviated through different angles by a prism. Explain the reason.
Give a reason, why the violet colour of white light deviated most and red colour of white light deviated least.
Write the approximate wavelength for red light.
