| Class | 10th |
| Subject | Science (NCERT) |
| Category | Important Questions |
The Human Eye and The Colourful World Class 10 Science Chapter 10 Important Question Answer
Q1. What type/nature of image is formed by the eye lens at retina ?
Ans – Image formed by the eye lens at retina is real and inverted.
Q2. What is the function of iris ?
Ans – It is behind the cornea. It controls the size of pupil.
Q3. Which phenomenon of light is responsible for twinkling of stars?
Ans – Atmospheric refraction.
Q4. Explain why the planets do not twinkle. Most Important
Ans – The planets are much closer to the earth, and are thus as extended sources. If we consider a planet as a collection of a large number of point-sized sources of light, the total variation in the amount of light entering our eye from all individual point-sized sources will average out to zero, thereby nullifying the twinkling effect.
Q5. Why do stars twinkle?
Ans – The twinkling of a star is due to atmospheric refraction of starlight. As the stars are very far away, they behave as almost a point source of light. When the light coming from stars enters the earth’s atmosphere, it gets refracted at different levels because of the variation in the air density. The path of rays of light coming from the star goes on varying slightly, the apparent position of the star fluctuates and the amount of starlight entering the eye flickers. So, sometimes, the star appears brighter and at some other time, fainter. Thus, the stars twinkle.
Q6. The prism split the incident white light into a band of colours. Write these colours name in sequence.
OR
Write the name of colours in sequence found after splitting of white light passing through a glass prism.
Ans – Colours in sequence : Violet, Indigo, Blue, Green, Yellow, Orange and Red.
It can be remember using VIBGYOR.
Q7. Why does the sky appear dark instead of blue to an astronaut ?
Ans – The sky appear dark instead of blue to an astronaut because of absence of atmosphere. In absence of atmosphere, there is no scattering.
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