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प्रश्न
Where is the near point of a person suffering from hypermetropia (or long-sightedness)?
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उत्तर
The near point of a person suffering from hypermetropia is more than 25 centimetres away.
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संबंधित प्रश्न
List three common refractive defects of vision. Suggest the way of correcting these defects.
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?
Which defect of vision can be rectified:
by using a convex lens?
Name the body part with which the terms myopia and hypermetropia are connected.
A student sitting in the last row of the class-room is not able to read clearly the writing on the blackboard.
How can this defect by corrected?
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.
A young man has to hold a book at arm's length to be able to read it clearly. The defect of vision is:
(a) astigmatism
(b) myopia
(c) presbyopia
(d) hypermetropia
The near point of a long-sighted person is 50 cm from the eye.
- Can she see clearly an object at:
- a distance of 20 cm?
- at infinity?
- To read a book held at a distance of 25 cm, will she need converging or diverging spectacle lenses?
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
Name the following:
The photosensitive pigment present in the rods of the retina.
Name the following:
The eye defect caused due to shortening of the eye ball from front to back.
State the main functions of the following:
Tears
Name the following:
The photosensitive pigment present in the rod cells of the retina.
Explain the Term: Astigmatism
Study the following diagram carefully and then answer the questions that follow. The diagram is depicting a defect of the human eye :
(i) Identify the defect shown in the diagram.
(ii) Give two possible reasons for the above defect.
Write scientific reason.
Nearsightedness, this defect can be corrected by using spectacles with concave lens.
Myopia may arise due to ____________.
Observe the figure and answer the following questions:
- Name the defect of vision represented in the above figure.
- State the reasons for this defect.
- How is it corrected?
- Draw the diagram to show the correction of this defect.
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.
