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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.
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.
In following diagram shows a thin beam of white light from a source S striking on one face of a prism.
What conclusion do you draw from the observation in part (b) above?
If a monochromatic beam of light undergoes minimum deviation through an equiangular prism, how does the beam pass through the prism, with respect to its base?
(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?
Name the radiation of a wavelength longer than 8 × 10−7 m.
Explain, why quartz prism is required for obtaining the spectrum of ultra-violet light?
Comment on the statement: ‘When any ray of white light is incident on a glass prism, it simply disperses it into its seven constituent colours.
Write the approximate wavelength for red light.
