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Questions
A student is unable to see clearly the words written on the blackboard placed at a distance of approximately 4 m from him. Name the defect of vision the boy is suffering from. Explain the method of correcting this defect.
Draw ray diagram for the:-
(i) defect of vision and also
(ii) for its correction.
A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?
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Solution
As the student is not able to clearly see the words written on the blackboard that is at a distance of approximately 4 m from him, the student is suffering from the defect called myopia or near-sightedness. A myopic eye has its far point nearer than infinity. It forms the image of a distant object in front of its retina. To correct a myopic eye, concave lens of a suitable focal length is used. The image is allowed to form at the retina by using a concave lens of suitable power.
(i) A myopic eye
(ii) Correction of myopia using concave lens
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RELATED QUESTIONS
Name the defect of vision in a person:
whose far point is less than infinity
Your friend can read a book perfectly well but cannot read the writing on blackboard unless she sits on the front row in class.
Is she short-sighted or long-sighted?
What is short-sightedness? State the two causes of short-sightedness (or myopia). With the help of ray diagrams, show:
(i) the eye-defect short-sightedness.
(ii) correction of short-sightedness by using a lens.
Name the following:
The eye defect caused due to shortening of the eye ball from front to back.
Name an old age eye defect. What happens in it?
Draw a ray diagram to show how Hypermetropia is defect can be corrected using a lens.
Choose the correct answer :
Presbyopia is a disease of _____________
Give Reason:
Deficiency of vitamin A causes night blindness.
Explain the Term: Hypermetropia
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.
