Class 10 Science - Chapter The Human Eye and the Colourful World NCERT Solutions | How does refraction take place in the at
How does refraction take place in the atmosphere? Why do stars twinkle but not the planets?
When the ray of light enters a glass prism, it bends because of the refraction of light. The light deviates from its original path because of the unique shape of the prism. Every coloured band has different speed and contains different angles of deviation. And then it will lead to the appearance of a band of seven colours which are the components of the white light. The various colours are seen- violet, Indigo, blue, green, yellow, orange and red and the acronym will be VIBGYOR.
Stars twinkling appear due to the atmospheric refraction of the starlight. When the starlight enters on the earth surface, refraction undergoes continuously with gradual changes in refractive index before it reaches the earth surface. The atmospheric physical condition does not remain stationary, the apparent position (when the star is slightly different from its original position) of the stars will also not be stationary. When the refractive index changes continuously due to which path of the light rays from the stars keeps on changing the path continuously. As the path of rays of light that comes from the stars, goes on varying slightly. The apparent position of the stars fluctuates and the starlight enters the eye- sometimes the star may appear brighter, and sometimes this effect is known as the twinkling effect.
Planets do not twinkle because they are very much closer to the earth in the comparison of stars and appear large to the human eyes. Thus, the planet can be seen as extended sources. When the light ray comes to our eyes from all the individual extended sources are constant. And there is no shifting occurs, so planets do not seem to twinkle.
More Questions From Class 10 Science - Chapter The Human Eye and the Colourful World
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Why do stars twinkle?
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What is the far point and near point of the human eye with normal vision?
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Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25 cm.
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Explain why the planets do not twinkle.
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What is meant by power of accommodation of the eye?
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The human eye forms the image of an object at its
(a) cornea. (b) iris. (c) pupil. (d) retina.
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A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?
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The least distance of distinct vision for a young adult with normal vision is about
(a) 25 m. (b) 2.5 cm. (c) 25 cm. (d) 2.5 m.
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A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision?
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Why does the sky appear dark instead of blue to an astronaut?
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Material
mediumRefractive
indexMaterial
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