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प्रश्न
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
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उत्तर
If the person is an old man, then the defect of vision is presbyopia. It usually occurs in old age when a person cannot see nearby objects clearly because of the loss of the eye's power of accommodation.
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संबंधित प्रश्न
In a Std. X class out of 40 students 10 students use spectacles, 2 students have positive power and 8 students have negative power of lenses in their spectacles.
Answer the following questions:
(1) What does the negative power indicate?
(2) What does the positive power indicate?
(3) Generally which type of spectacles do most of the students use?
(4) What defect of eyesight do most of the students suffer from?
(5) Give two possible reasons for the above defect.
the biological/technical terms for the lens of eye losing flexibility resulting in a kind of long-sightedness in middle aged people.
Which defect of vision can be rectified:
by using a convex lens?
The near-point of a person suffering from hypermetropia is at 50 cm from his eye. What is the nature and power of the lens needed to correct this defect? (Assume that the near-point of the normal eye is 25 cm).
A person cannot see the distant objects clearly (though he can see the nearby objects clearly). He is suffering from the defect of vision called:
(a) cataract
(b) hypermetropia
(c) myopia
(d) presbyopia
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
Which part of the eye is grafted in a needy patient from a donated eye?
Differentiate between members of the following pair with reference to what is asked in the bracket.
Rods and cones (sensitivity).
A student cannot see a chart hanging on a wall placed at a distance of 3 m from him. Name the defect of vision he is suffering from. How can it be corrected? Draw ray diagrams for the (i) defect of vision and also (ii) for its correction.
Draw a ray diagram to show how Hypermetropia is defect can be corrected using a lens.
Name the following:
The photosensitive pigment present in the rod cells of the retina.
Choose the correct answer :
Presbyopia is a disease of _____________
Name the common defects of the eye.
Differentiate between:
Myopia and Hypermetropia.
What are the causes of ‘Myopia’?
Myopia and hypermetropia can be corrected by:
Assertion: Concave mirrors are used as reflectors in torches, vehicle head lights and in search lights.
Reason: When an object is placed beyond the center of curvature of a concave mirror, the image formed is real and inverted.
When do we consider a person to be myopic or hypermetropic? Explain using diagrams how the defects associated with myopic and hypermetropic eye can be corrected?
