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SCIENCE & TECHNOLOGY Chapter 11 : Human Eye and Colourful World

1. What is meant by power of accommodation of the eye? (1mark)
2. 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? (1mark)
3. Write down the function of the iris in the human eye? (1mark)

4. Name the muscles responsible for bringing change in the focal length or the lens. (1mark)

5. Which cells of the retina are responsible for two light (black and white) vision? (1mark)

6. Why does it take some time to see objects in a dim room when you enter the room from bright sunlight outside? (2 marks)
7. What is Tyndall effect? Explain with an example. (2 marks)

8. Draw a labelled diagram to show the formation of a rainbow. (2 marks)

9. Define the power of accommodation. What is the value power of accommodation for a young adult with normal vision? (2 marks)
10. The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem? (2 marks)
11. Why is a normal eye not able to see clearly the objects placed closer than 25 cm? (2 marks)

12. A person wears glasses of power -2.5 D. Is the person far sighted or near sighted? What is the far point of the person without glasses? (3 marks)
13. How do you account for the red colour of the sun during sunrise and sunset? (3 marks)

14. Explain Myopia with the help of suitable ray diagrams. How can this defect of vision be corrected?
A boy uses spectacles of focal length-50 cm. Name the defect of vision he is suffering from.

Compute that power of this lens. (5 marks)

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