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प्रश्न
What is atmospheric refraction? Use this phenomenon to explain the following natural events:
Twinkling of stars
Draw diagrams to illustrate your answers.
Explain with the help of a labelled diagram, the cause of twinkling of stars.
Why do stars twinkle?
Why do stars twinkle ? Explain.
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उत्तर १
Stars emit light on their own; when this light travels through the Earth's atmosphere which has variable optical density, the continuously changing atmosphere refracts the light from the stars in different amounts from one moment to the next. The light seems to be bright and dim as it keeps changing because of continuous refraction through the different layers of the atmosphere of the Earth. Hence, we say light twinkles at night.
उत्तर २
Stars are considered to be point sources of light as they are far away from the Earth. The light coming from stars, on entering the atmosphere, gets bent because of refraction. Since the atmospheric physical conditions are continually changing, the apparent position of the star also keeps fluctuating. The amount of light entering the eye also varies because different amount of light bends at every instant. This is what gives the stars a twinkling appearance
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संबंधित प्रश्न
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
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
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
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?
- Do you think that the students’ conclusion is correct?
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?
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.
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?
