Human eyes and Colorful world (Guess Questions

QUESTIONS FROM CBSE EXAMINATION PAPERS:
1. What is the role of pupil in a human eye?
2. What is the range of vision of a normal human eye?
3. Name the part of the human eye that helps in changing the focal length of the eye lens.
4. Which coloured component bends the least during the dispersion of white light through prism?
5. Name the part of the eye
(a) That controls the amount of light entering into the eye.
(b) That has real, inverted image of the object formed on it.
6. A person is advised to wear spectacles with convex lenses. State the defect of vision he is suffering from.
7. Draw a ray diagram to show the angle of deviation when a ray of light passes through a glass prism.
8. When one enters a dim-lit room from bright  light, one is unable to see the objects in the room for some time. Why?
9. What is meant by near point of a human eye?
10. A person is advised to wear spectacles with concave lenses. What type of defect of vision is he suffering from?
11. What will be the observed colour of the sky on a planet where there is no atmosphere? Why?
12. Name the component of white light that deviates the least and the component that deviates the most while passing through a glass prism.
13. Why does the sky look blue on a clear day?
14. Why is red colour selected for danger signal lights?
15. Why does the sun appear reddish at sunrise?
16. What kind of lens is used in the spectacles of a person suffering from myopia?
17. Name the defect of vision when : (i) power of the eye is too great. (ii) focal length of the eye lens is too great.
18. Why is red light used as a universal danger signal?
19.  Name the defect of vision caused when:  (i) cornea is not perfectly spherical. (ii) power of accommodation of the eye decreases.
20. What is stereopsis as applied to human eyes? Explain.

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