CBSE Guess > Papers > Important Questions > Class X > Science > Physics > Optical Instruments By ; Mr. Nagesh

Physics (Light)

1. Explain the following terms in relation to the defects of vision and corrections provided for them: Myopia (near sightedness), Hypermetropia (Long/far sightedness), Astigmatism, Bifocal lenses.
2. Describe with the help of a ray diagram how a person with myopic vision can be helped by spectacles.
3. What is a simple microscope? Draw a diagram to show the image formation by a simple microscope when the object is placed at: Infinity, on the near point.
4. What is the magnification obtainable by simple microscope?
5. In what S.I units is the power of lenses stated? A convex lens has a focal length of 50cm. calculate its power.
6. What are the differences between the simple and compound microscope? Draw a well labeled ray diagram showing the image formation by the compound microscope. State the formula used to calculate the magnification produced by the compound microscope. What is the maximum magnification generally produced by the compound microscope?
7. Explain how we see different colours of an object. Why it is that some people are not able to distinguish between different colours? The chicken wakes up with the sunrise and sleeps with the sunset. How does it manage?
8. Find the focal length of a concave lens of power -2D.
9. State two main causes of a person developing Myopia/ Hypermetropia.
10. The far point of a myopic person is 150cm in front of eye. Calculate the focal length and the power of the lens required to enable him to see distant objects clearly.
11. How does a convex lens behave as a magnifier? Find the magnification of this lens and suggest a method to improve magnification.
12. Write the relation between the power and focal length of the convex length and its sign conventions.
13. What is the function of rod and cone cells in the human eye? Write a note on the defects of human eye.
14. Draw a labeled diagram of human eye. Write the functions of Cornea, Iris, Pupil, eye lens and retina.
15. A boy has spectacles of focal length -50cm. Which defect he is suffering from? Compute the power of lens