1 mark questions
- What is light?
- Write two similarities between eye and camera.
- What is near point of the eye?
- What is the meaning of saying "the power of a lens is 1 diopter"?
- What is meant by the focal length of a lens?
- Define principal focus.
- What is the distance of distinct vision?
- What is range of vision?
- What is center of curvature?
- What is optical instrument?
- Write down two types of optical instruments.
- The magnification is more than one, what does it mean?
- What is optical centre?
- Write down the mathematical relation among focal length, image distance, and object distance.
- What is the mathematical relation between power of lens and focal length?
- What is the function of optic nerve?
- What is retina?
- What are two defects of visions?
- What are the two types of lens?
- What is a binoculars?
- What is the size of the image if it is placed at 2F?
2 marks questions
1. Write any two differences between real and virtual image.
2. Distinguish between convex and concave lenses.
3. Explain with two reason that when sunlight is focused on a piece of paper with the help of a
convex lens, the paper will burn.
4. What do you mean by the defect of vision? How many types of this defect of vision do you know?
5. Write two causes of short sightedness.
6. Write two causes of long sightedness.
7. Write any two differences convex lens and concave lens.
8. Write any two utilities of concave lens.
9. Write any two utilities of convex lens.
10. Write down any two differences between myopia and hypermetropia.
11. Define radius of curvature and center of curvature.
12. What is principle axis and principle focus of a lens?
13. What is the focal length of a lens whose power is one diopter and mention what type of lens is
that?
14. An object is placed 5 cm in front of convex lens whose focal length is 2 cm. Find the image
distance.
15. Draw a diagram to show how a convex lens can be used as a magnifying glass.
16. What is far point and near point?
17. Why is the human eye unable to focus on an object within a range of 10 cm?
18. What are cornea and iris?
19. Focal length of a convex lens is. 2 cm. An object of height 1 cm is placed at a distance of 1 cm
from the lens. Draw a ray diagram and write the nature of the image formed.
20. What is the focal length of lens whose power is one diopter and mention what type of lens is that?
21. Draw a clear ray diagram of the image formed when an object is placed 40 cm away from a lens
having the focal length 20 cm.
22. When a person enters a nearly dark room from bright sunny day he cannot see at once the objects
inside the room. Explain why?
23. Differentiate between f and F.
3 marks questions
24. Completer the given ray diagram. Write the nature of image formed. Also write one use of the
given lens.
25. Complete the given ray diagram and write the nature of image formed.
26. Power of the given lens is 25 D.
i. Find the distance FO.
ii. Draw a ray diagram of the image formed by this lens when an object is kept at 7 cm away
from the lens. Also write any three natures of the image so formed.
27. What is meant by the power of the lens? In What unit can it be expressed? Calculate the power of
lenses having the focal lengths i. 2m ii. 0.5m
28. If an object is placed at a distance twice the focal length from a lens. Use a ray diagram to show
where the image will be formed.
29. What is the focal length of a lens whose power is one diopter and mention what type of lens is
that?
30. An object is place 3cm from a convex lens of focal length 2cm. Calculate the image distance.
Show by means of ray diagram. Find the power of the lens and the magnification.
31. Define lens, optical center, principle axis and focus of the lenses.
32. What do you mean by defect of vision? How can we correct the defect of vision both short-
sightedness and long-sightedness? Explain with diagram.
33. Give two causes of short-sightedness. Draw separate ray diagrams to explain where the images
are formed before and after the removal of this type of defect.
34. Give two causes of long-sightedness. Draw separate ray diagrams to explain where the images are
formed before and after the removal of this type of defect.
35. Study the figure and answer the following:
i. What type of defect of vision is shown in the figure? What should be done to correct it?
ii. Write two causes of such defect.
36. A magnifying lens has power +6D. What distance should it be placed to read a book? If a person
is wearing same power spectacles, where should he keep his book to read it without using
spectacles?
37. What is meant by the focal length of a convex lens? A convex lens has a focal length of 3 cm. If a
candle is placed at a distance from the lens equal to twice the focal length,
i. How far from the lens will be formed the image? Use a ray diagram.
ii. What is the magnification?
iii. What is the power of the lens?
38. Lens is formed form the group of prisms. Explain with diagram.
4 marks questions
39. What do you mean by magnification of lens ? Prove that magnification M = I/O = v/u
40. A student can’t properly see the letters on book. What types of defect of vision is he suffering
from? What should be done to correct it and why? Draw its corrected vision.
41. What is myopia? Draw its diagram and also draw the correct vision of such defect of eye.
42. A burning candle is place at 3 cm away from convex lens of focal length 2cm. Draw a ray
diagram of this condition. Also calculate the power of lens. Write one use of the lens.
43. Look at the figures given below and answer the followings:
i. Identify the defect in each case.
ii. Write the causes of such defects.
iii. How can be given defects removed? Show with suitable ray diagram.
44. Focal length of a convex lens is 2 cm. An object of height 2cm is placed at a distance of 2 cm
from the lens. Draw a ray diagram and write the nature of image.
45. If lighting candle is placed at the distance of 4 cm from a convex lens having the focal length of
3cm, draw a ray diagram to show the formation of image. Calculate the magnification of the lens.
46. Complete the ray diagram of concave lens if the object is placed between F and 2F. Write the
nature of image.
47. Draw a neat and labeled ray diagram showing the image formed by a convex lens when object is
i. At 2F
ii. Beyond 2F
48. Draw a neat and labeled ray diagram showing the image formed by a convex lens when the object
is placed.
i. At focus (F)
ii. Between F ad 2F. Also, write down the characteristics of the image formed.
49. A concave lens of focal length 20 cm is kept to see the burning candle of 9cm which is 10cm far
from the lens. Calculate
a. power of lens b. image distance
c. magnification d. image height
e. Construct the ray diagram
d. Write the nature of the image.
50. Study the figure and answer the following:
i. What type of defect of vision of eye is given in the figure?
ii. What should be done to remove this type of defect?
iii. Write a cause of this type of defect of vision.
iv. Draw the correction for this defect.
51. Study the figure and answer the following:
i. What type of defect of vision of eye is given in the figure?
ii. What should be done to remove this type of defect?
iii. Write a cause of this type of defect of vision.
iv. Draw the correction for this defect.
52. Draw a labeled diagram of human eye. Define near point and far point.
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