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प्रश्न
Why does the sky appear blue on a clear day?
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उत्तर
The sky appears blue on a clear day because of the scattering of blue light by the air molecules in the earth's atmosphere. The air molecules are much smaller compared with the wavelength of visible light. Therefore, they scatter light of shorter wavelengths more easily and effectively than light of longer wavelengths. Hence, blue light gets scattered very easily because of its shorter wavelength compared with other colours, such as red, orange and yellow.
संबंधित प्रश्न
What is atmospheric refraction? Use this phenomenon to explain the following natural events:
Twinkling of stars
Draw diagrams to illustrate your answers.
What is atmospheric refraction? Use this phenomenon to explain the following natural events:
Advanced sun-rise and delayed sun-set.
Draw diagrams to illustrate your answers.
Name two effects produced by the atmospheric refraction.
Atmospheric refraction causes advance sunrise and delayed sunset. By how much time is:
sunrise advanced?
Atmospheric refraction causes advance sunrise and delayed sunset. By how much time is:
sunset delayed?
State whether the following statement is true or false:
The planets twinkle at night due to atmospheric refraction of light.
Why do stars seem higher than they actually are? Illustrate your answer with the help of a diagram.
The twinkling of stars is due to atmospheric:
(a) reflection of light
(b) dispersion of light
(c) interference of light
(d) refraction of light
The stars twinkle but the planets do not twinkle at night because:
(a) the stars are small but the planets are large
(b) the stars are very large but planets are small
(c) the stars are much nearer but planets are far off
(d) the stars are far off but planets are nearer to earth
The day is longer on the earth by about 4 minutes because:
(a) the earth is round in shape
(b) the earth rotates on its axis
(c) the earth revolves around the sun
(d) the earth has atmosphere
We know that light refracts (or bends) when it goes from one medium to another. Now, the atmosphere contains only air. Then how does light get refracted on passing through only air in the atmosphere?
A student claims that because of atmospheric refraction, the sun can be seen after it has set, and the day is, therefore, longer than if the earth had no atmosphere.
- What does the student mean by saying that the sun can be seen after it has set?
- Do you think that the students’ conclusion is correct?
State one effect produced by the scattering of light by the atmosphere.
A star sometimes appears brighter and some other times fainter. What is this effect called? State the reason for this effect.
Explain why the planets do not twinkle but the stars twinkle.
The air layer of the atmosphere whose temperature is less than the hot layer behave as optically:
Refraction of light by the earth’s atmosphere due to variation in air density is called ____________.
