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Question
A star sometimes appears brighter and some other times fainter. What is this effect called? State the reason for this effect.
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Solution
A star sometimes appears brighter and some other times fainter, this effect is called as twinkling effect. This effect arises due to atmospheric refraction. Our atmosphere is constantly moving. Light travelling from the stars gets bent in different directions making them twinkle.
RELATED QUESTIONS
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 the phenomenon which causes the twinkling of stars.
Atmospheric refraction causes advance sunrise and delayed sunset. By how much time is:
sunrise advanced?
State whether the following statement is true or false:
The planets twinkle at night due to atmospheric refraction of light.
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
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
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
Explain the refraction of light through a triangular glass prism using a labelled ray diagram. Hence define the angle of deviation.
