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प्रश्न
Explain why the planets do not twinkle.
Explain why, the planets do not twinkle at night.
उत्तर
Planets are much closer to the Earth and are seen as extended sources. So, a planet may be considered a collection of a large number of point-sized light sources. Although light coming from individual point-sized sources flickers but the total amount of light entering our eye from all the individual point-sized sources averages out to be constant. Thereby, planets appear equally bright and there is no twinkling of planets.
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संबंधित प्रश्न
Name two effects produced by the atmospheric refraction.
Atmospheric refraction causes advance sunrise and delayed sunset. By how much time is:
sunrise advanced?
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 atmospheric refraction of light causes the twinkling of:
(a) planets only
(b) stars only
(c) planets and stars
(d) stars and satellites
As light from a far off star comes down towards the earth:
(a) it bends away from the normal
(b) it bends towards the normal
(c) it does not bend at all
(d) it is reflected back
Due to atmospheric refraction of sunlight, the time from sunrise to sunset is lengthened by about:
(a) 6 minutes
(b) 2 minutes
(c) 4 minutes
(d) 5 minutes
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?
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.
Do you think that the students conclusion is correct?
State two effects produced by the scattering of light by the atmosphere.
Which of the following is not caused by the atmospheric refraction of light?
(a) twinkling of stars at night
(b) sun appearing higher in the sky than it actually is
(c) sun becoming visible two minutes before actual sunrise
(d) sun appearing red at sunset
A star sometimes appears brighter and some other times fainter. What is this effect called? State the reason for this effect.
The air layer of the atmosphere whose temperature is less than the hot layer behave as optically:
Assertion: Sky appears blue in the day time.
Reason: White light is composed of seven colours.
Explain the refraction of light through a triangular glass prism using a labelled ray diagram. Hence define the angle of deviation.
How does refraction take place in the atmosphere? Why do stars twinkle but not the planets?
