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प्रश्न
A person cannot read newspaper placed nearer than 50 cm from his eyes. Name the defect of vision he is suffering from. Draw a ray diagram to illustrate this defect. List its two possible causes. Draw a ray diagram to show how this defect may be corrected using a lens of appropriate focal length.
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उत्तर
The person is suffering from Hypermetropia i.e. far-sightedness.
Hypermetropia is caused due to:
(i) The focal length of the eye lens is too long
(ii) Decrease in the length of the eyeball
This defect can be corrected using convex lens of appropriate focal length.
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संबंधित प्रश्न
Name any two defects of vision which can be corrected by using spectacles.
Where is the near point of a person suffering from hypermetropia (or long-sightedness)?
What is long-sightedness? State the two causes of long-sightedness (or hypermetropia). With the help of ray diagrams, show:
(i) the eye-defect long-sightedness.
(ii) correction of long-sightedness by using a lens.
Differentiate between members of the following pair with reference to what is asked in bracket.
Myopia and hyperopia (cause of the defect)
What is Hypermetropia (far sightedness)?
Name the following:
The photosensitive pigment present in the rod cells of the retina.
The diagram alongside represents a section of a mammalian eye.
(i) Label the parts 1 to 5 of the diagram.
(ii) State the function of the parts labelled 4 and 5.
(iii) With the help of a diagram show the short sightedness.
Give Reason:
Deficiency of vitamin A causes night blindness.
Nearsightedness: elongated eyeball : : farsightedness: _______
A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard. What advice will a doctor give to her? Draw ray diagram for the correction of this defect.
