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
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?
(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.
Write the approximate wavelengths for blue.
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.
Name the radiation of a wavelength longer than 8 × 10−7 m.
Which colour of white light travels slowest, in glass?
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?
