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प्रश्न
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?
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उत्तर
- The student is suffering from myopia (short-sightedness)
- To correct his defect, he should use concave lenses in his spectacles.
APPEARS IN
संबंधित प्रश्न
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?
What is the other name for
hypermetropia
A man can read the number of a distant but clearly but he finds difficulty in reading a book.
What type of spectacle lens should he use to correct the defect?
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 person having short-sight cannot see objects clearly beyond a distance of 1.5 m. What would be the nature and power of the corrective lens to restore proper vision?
The defect of vision in which the eye-lens of a person gets progressively cloudy resulting in blurred vision is called:
(a) myopia
(b) presbyopia
(c) colourblindness
(d) cataract
Have a look at the posture of this girl who is reading a book and answer the questions which follow:
Name the problem she is facing.
State the main functions of the following:
Tears
Name the following:
The photosensitive pigment present in the rod cells of the retina.
Write whether the following is true or false:
A convex lens is used for correcting myopia.
Have a look at the posture of this woman who is reading a book and answer the questions which follow:
What kind of looking glasses she needs?
A person is unable to see objects distinctly placed within 50 cm from his eyes.
(a) Name the defect of vision the person is suffering from and list its two possible causes.
(b) Draw a ray diagram to show the defect in the above case.
(c) Mention the type of lens used by him for the correction of the defect and calculate its power. Assume that the near point for the normal eye is 25 cm.
(d) Draw a labeled diagram for the correction of the defect in the above case.
Give Technical Term:
The path which responsible for protecting the eye from sweat.
Due to elongation of _______ and increase in curvature of the eye lens, a person cannot see distant objects clearly.
Nearsightedness: elongated eyeball : : farsightedness: _______
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.
Have a look at the posture of this girl who is reading a book and answer the questions which follow:
 |
- Name the problem she is facing.
- What are the two conditions shown in sections A and B of the eye as applicable to her.
- What kind of reading glasses does she need?
 |
 |
| A | B |
