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Question
Give Reason:
Why do we see clearly in the central region of the retina?
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Solution
The central region of the retina has fovea centralis, with the yellow spot area surrounding it. There are only cone cells responsible for clear vision and details of the objects.
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RELATED QUESTIONS
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
The near point of a long-sighted person is 50 cm from the eye.
(a) Can she see clearly an object at:
(i) a distance of 20 cm?
(ii) at infinity?
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
Name the following:
The photosensitive pigment present in the rods of the retina.
Write whether the following is true or false:
A convex lens is used for correcting myopia.
Name the common defects of the eye.
Give Reason:
Older people require glasses to read and write.
Differentiate the eye defects: Myopia and Hypermetropia
Assertion: Myopia is the defect of vision in which a person cannot see distant objects clearly.
Reason: This due to eye-ball being too short.
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.
