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प्रश्न
Name the defect of vision in which the eye-lens loses its power of accommodation due to old age.
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उत्तर
Presbyopia is the defect of vision because of which the eye lens loses its power of accommodation because of old age.
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संबंधित प्रश्न
About 45 lac people in the developing countries are suffering from corneal blindness. About 30 lac children below the age of 12 years suffering from this defect can be cured by replacing the defective cornea with the cornea of a donated eye. How and why can students of your age involve themselves to create awareness about this fact among people?
A student suffering from myopia is not able to see distinctly the objects placed beyond 5 m. List two possible reasons due to which this defect of vision may have arisen. With the help of ray diagrams, explain
(i) why the student is unable to see distinctly the objects placed beyond 5 m from his eyes.
(ii) the type of the corrective lens used to restore proper vision and how this defect is corrected by the use of this lens.
(b) If, in this case, the numerical value of the focal length of the corrective lens is 5 m, find the power of the lens as per the new Cartesian sign convention
What is the other name of old age hypermetropia?
A student sitting in the last row of the class-room is not able to read clearly the writing on the blackboard.
Name the type of defect he is suffering from.
A person can read a book clearly only if he holds it at an arm's length from him. Name the defect of vision:
if the person is an old man
Differentiate between members of the following pair with reference to what is asked in the bracket.
Rods and cones (sensitivity).
What eye defect is hypermetropia? Describe with a ray diagram how this defect of vision can be corrected by using an appropriate lens.
Name the following:
The photosensitive pigment present in the rod cells of the retina.
Rewrite the following table so as to match second and third column with first column.
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Column I
|
Column II
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Column III
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|
(i) Myopia
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Old age problem
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Bifocal lens
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|
(ii) Presbyopia
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Nearsightedness
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Concave lens.
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In what two whys is a yellow spot different from the blind spot?
Differentiate between:
Myopia and Hypermetropia.
Draw a neat labeled diagram to show how hypermetropia can be rectified.
Give Technical Term:
The type of lens used to correct myopia is
What type of lens is used to correct Hypermetropia?
Nearsightedness: elongated eyeball : : farsightedness: _______
Which of the following statement is correct?
A person needs a lens of power –4.5 D for correction of her vision.
- What kind of defect in vision is she suffering from?
- What is the focal length of the corrective lens?
- What is the nature of the corrective lens?
Observe the figure whether it is correct or not and explain the phenomenon.
Observe the following diagram and answer questions following it:
- Identify the defect of vision shown.
- List its two causes.
- Name the type of lens used for the correction of this defect.
Given alongside is a diagram depicting a defect of the human eye. Study the same and answer the questions that follow:
 |
- Name the defect shown in the diagram.
- Give two possible reasons for this defect.
- Name the parts labelled 1 to 4.
- Name the type of lens used to correct this eye defect.
- Draw a labelled diagram to show how the above mentioned defect is rectified using the lens named above.
