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प्रश्न
Differentiate between members of the following pair with reference to what is asked in the bracket.
Rods and cones (sensitivity).
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उत्तर
Rods: They are sensitive to dim light but do not respond to colour.
Cones: They are sensitive to bright light and are responsible for colour vision.
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संबंधित प्रश्न
Millions of people in the developing countries of the world are suffering from corneal blindness. These persons can be cured by replacing the defective cornea with the cornea of a donated eye. A charitable society of your city has organised a campaign in your neighbourhood in order to create awareness about this fact. If you are asked to participate in this mission, how would you contribute in this noble cause?
(i) State the objective of organising such campaigns.
(ii) List two arguments which you would give to motivate the people to donate their eyes after death.
(iii) List two values which are developed in the persons who actively participate and contribute in such programmes.
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
Which defect of vision can be rectified:
by using a concave lens?
What is the scientific name of
short-sightedness
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 a young man
List two causes of presbyopia. Draw labelled diagram of a lens used for the correction of this defect of vision.
Given below is a diagram depicting a defect of the human eye? Study the same and answer the question that follow:
Name the parts labeled 1 to 4.
Nearsightedness: elongated eyeball : : farsightedness: _______
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.
