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HUMAN EYE & DISPERSION OF LIGHT***  CRASH QUIESTIONEER SS2 2011

1.         Make a diagram to show how hypermetropia is corrected?

2.       Define the term “power of accommodation” of human eye.

3.         What happens to the eye when you enter a darkened cinema hall from bright sunshine?  Give reason for your answer.

4.         Explain why, we cannot see our surrounding clearly when we enter a darkened cinema hall from the sunshine but our vision improves after some time.

5.         Give the usual name of the following (a) the screen on which image is formed in the eye.                                                                                    (b) The part which controls the amount of light entering the eye.

6.         What is meant by the ‘persistence of vision’

7.         How do we see colour.? Why does sky appears blue

8.        What is the colour blindness? What kind of retinal cells are lacking in a person suffering from this defect?

9.         (a)What are the two types of light sensitive cells on the retina of a cell of an eye ? (b) Which of these cells respond to colour ? (c)Which of these cells respond to intensity of light?

10.        A child sitting in the class-room is not able to read clearly the writing on the black-board.  (a) Name the type of defect from which he is suffering ? (b) With the help of a ray diagram, show how this defect can be remedied.

11.      What are the main defects of human eye? Explain their causes and suggest remedies. Draw Figure?

12.     A man can read a  book. clearly but he finds difficulty in reading the number   of a distant bus (a)From which defect of the eye is he suffering? (b) What type of spectacle lens should he use to correct the defect?

13.      Differentiate between myopia and hypermetropia.?Give causes and treatment?

14.    Ciliary muscles of human eye can be stretched or relaxed. How does it help in the normal functioning of the eye?

15.    Why does a piece of red cloth appear red? Describe and explain the appearance of a piece of red cloth when it is illuminated by (i) white light (ii) red light (iii) blue light.

16.    In the formation of spectrum of white light by a prism :-(i) Which colour are deviated paints?                                                                                            (ii) Which colour is deviated most?

17.     A beam of red light is allowed to fall in turn on (a) black cloth, (b) red cloth, (c) white cloth, and (d) blue cloth. Describe and explain the appearance in each case.

18.     A beam of sunlight falls on a mixture of blue and yellow pigments. Which colour of white light will be reflected from this mixture? Why.

19.      Explain why, we cannot see our surrounding clearly when we enter a darkened cinema hall from the sunshine but our vision improves after some time.

20.      Give the usual name of the following (a) the screen on which image is formed in the eye.                                                                                    (b) The part which controls the amount of light entering the eye.

21.    A man can read the number   of a distant bus clearly but he finds difficulty in reading a  book. (a)From which defect of the eye is he suffering? (b) What type of spectacle lens should he use to correct the defect?

22.    What is cataract ? Give the diseases in which eye donation is not permited?

23.    What is critical angle and how it is related to refractive index of the medium

24.     A convex mirror used on a bus has a focal length of 200 cm. If a scooter is located at 400 cm from this mirror, find the position , nature and magnification of the image formed in the mirror.

25.     An object 15 cm length is placed at a distance of 10 cm in front of a convex mirror of focal length 15 cm. Find the position, nature and size of the image formed.

26.     A concave lens has a focal length of 15 cm. At what distance should an object 10 cm long be placed so that it forms an image at 10 cm from the lens? Find the nature and size of the image formed.

27.     Name the four common defects of vision and state the cause of each defect. A person cannot see distinctly objects placed beyond 2 m. State the nature and focal length of the lens which could be used to correct this defect.

28.    An object is placed at 20 cm from a lens of focal length 10cm. The lens produces an erect and diminished image, Draw a ray diagram showing the image formation by the lens. Find the position of the image formed by the lens.

29.     Is it necessary that an optically denser medium must have greater mass density?Give an example.

30.     How does the size of an image changes when an object is moved away from a concave mirror?

31.     Explain, why the length of the day time increases by 4 minutes.

32.     Name the principles involved in the formation of rainbow.

33.    State two applications of total internal reflection.

34.    Refractive index of media A, B, C and D are:   A [1.53], B [1.32]  C [1.44] &  D [1.65 ] .In  which of the four      media  light travels is (i)Fastest (ii)Slowest  [1]

35.     The  ciliary  muscles of a normal eye  are in their most relaxed condition . Give  an estimate of the focal          length of the eye lens in this condition . [1]

36.    A person is able to see objects clearly only when these are lying at distances b/w 50cm and  300cm from his eye. (a) What kind of defects of vision he is suffering from?  (b) What kind  of lenses will be required to  increase his range of vision from 25cm to infinity? Explain & show by calculation [2]

37.    A person is able to see objects clearly only when these are lying at distances b/w 100 cm and  80cm from his eye. (a) What kind of defects of vision he is suffering from?  (b) What kind  of lenses will be required to  increase his range of vision from 25cm to infinity? Explain & show by calculation [2]

38.    Compare the phenomenon of mirage & looming( Give the condition )

39.    A compound lens is made of two lenses in contact having power – 24.0D and + 4.0 D. An object is placed 15 cm from it. Find the position and nature of the image.              [3]

40.     A man cannot see object closer than 1m from the eye clearly, what is the power of corrective lens he should use? Name the nature of the lens and defect of the eye? [3]

41.     Name the part of the eye that (i) determines the color of a person’s eye.  (ii) Controls the amount of light entering the eye.  (iii) focuses objects at different distances on the screen of eye. [3]

42.     A truck driver sees the image of a car following at a distance of 30 m in the rear view   mirror of  radius of               curvature 3m. find the nature , position and the magnification of the image.     [3]

43.     (i)  A ray of light ,after refraction through a diverging lens , emerges parallel to the principal axis . Draw a  ray   diagram to show the incident ray & its corresponding emergent ray (ii) The velocity of light in a medium X is 121000 km/ s. What is its refractive index [3]

44.    Give reasons for the following:  (i) The sky appears to be blue during day time .  (ii) The sky near the horizon appears to have a reddish look at the time of sunset and sunrise.(iii)The stars appear to twinkle. 

45.    An object 5 cm in length is held 25 cm away from a converging mirror of radius of curvature 50 cm. Find  the nature & position of image. [3]

46.     (i) What is the near point & far point for a person with nearsightedness  ? (ii) Name the defect of eye which can not be corrected by any spectacles.What is the Cause of it.How can  it corrected.[3]

47.     What do you mean by angle or deviation in prisim?

48.    What do you mean by scattering light or tyndall effect?

49.     Why does the sky appear dark instead of blue to an astronaut.

50.     What is presbyopia? How it is caused & how it is corrected?

51.    What is meant by the far point, near point and the least distance distinct vision?

52.     Why does it take some time to see to see object in a dim room when you enter the room from bright sunlight outside?

53.     A person with a defective eye-vision is unable to see the object nearer than 1.5m. He wants to read books at distance of 30 cm. Find the nature, focal length and power of the lens he needs in his spectacles?

54.    .What is dispersion? Which color of light deviates more on passing through a prism? When two prisms are placed together with one inverted and white light is passed, what will be the result?

55.    What are the values for the angle of incidence and angle of reflection for normal incidence?

56.     What is the relation between the critical angle and the refractive index for a medium?

57.    Explain the phenomenon of mirage in deserts and looming in the seas? Support your answer with diagrams. Why does a diamond glitter more? Which phenomenon does optic fiber work upon?

58.    . What will be the colour of the red rose when placed separately in white light and blue light? Give reasons for your answer. 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.

59.    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.

60.    .Draw a labeled diagram of human eye. Write the functions of Cornea, Iris, Pupil, eye lens and retina.

61.    A boy has spectacles of focal length -50cm. Which defect he is suffering from? Compute the power of lens

62.    How we can see the movies>how many frames are needed for normal film movie and How many for slow motions scenes?

63.    What is the importance having  two eyes in front of face?

64.    Which part of the eye is transplanted during eye donation?

65.    How Iris control the size of pupil and amount of light?

66.    (a) Molecules of air and other particles in the atmosphere are bigger than wavelength of visible light (b) Light of shorter wavelengths at the blue end are scattered more than the red light whose wavelength is 1.8 times. (c) The scattered blue light do not enters our eyes

67.    The far point of a myopic person is 80cm in front of the eye. What is the nature and power of the lens required to correct the problem? ( 3 Marks )

68.    Why Danger’ signal lights are usually red in color

 Prepared by bhatiasir For 2011 term SA2 for PCC

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