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Question
Explain the Term: Cataract
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Solution
Cataract: It is a condition in which the lens turns opaque and the vision is cut down even to total blindness. It can be corrected by surgically removing the lens and by using spectacles with highly convex lense.
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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
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.
- How can this defect by corrected?
Explain with the help of labelled ray-diagram, the defect of vision called hypermetropia, and hot it is corrected by a lens.
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
- if the person is a young man
Explain the Term: Hypermetropia
What type of lens is used to correct Hypermetropia?
Myopia and hypermetropia can be corrected by:
Myopia may arise due to ____________.
Observe the figure whether it is correct or not and explain the phenomenon.
Name the following:
Two kinds of accomodations.
