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प्रश्न
Why is the colour red used as a sign of danger?
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उत्तर
In the visible light, the wavelength of red light is longest, the light of red colour is scattered least by the air molecules of the atmosphere and therefore the light of red colour can penetrate to a longer distance. Thus, red light can be seen from the farthest distance as compared to the other colours having the same intensity. Hence, it is used for danger signal so that the signal may be visible from the far distance even in fog, etc.
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संबंधित प्रश्न
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?
(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.
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?
Give a reason, why the violet colour of white light deviated most and red colour of white light deviated least.
