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Question
Why do stars seem higher than they actually are? Illustrate your answer with the help of a diagram.
Solution
Stars seem higher than they actually are because of the phenomenon of atmospheric refraction. This can be understood with the help of given diagram. When the light from a star descends to the earth's surface, it passes through the different layers of the atmosphere. The atmospheric air at higher levels is rarer and the air near the earth's surface is denser, and the light from the star bends more sharply when it passes through the denser layer of air.
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RELATED QUESTIONS
The correct sequencing of angle of incidence, angle of emergence, angle of refraction and lateral displacement shown in the following diagram by digits 1, 2, 3 and 4 is:
(a) 2, 4, 1, 3
(b) 2, 1, 4, 3
(c) 1, 2, 4, 3
(d) 2, 1, 3, 4
Atmospheric refraction causes advance sunrise and delayed sunset. By how much time is:
sunset delayed?
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
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
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?
State two effects produced by the scattering of light by the atmosphere.
Why does the sky appear blue on a clear day?
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
Explain why the planets do not twinkle but the stars twinkle.
Assertion: Sky appears blue in the day time.
Reason: White light is composed of seven colours.
