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प्रश्न
To read a book held at a distance of 25 cm, will she need converging or diverging spectacle lenses?
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उत्तर
To read a book held at a distance of 25 cm, the person, who is long-sighted, will need converging lenses.
संबंधित प्रश्न
List three common refractive defects of vision. Suggest the way of correcting these defects.
A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision?
Name the defect of vision in a person:
whose far point is less than infinity
Which defect of vision can be rectified:
by using a concave lens?
Which defect of vision can be rectified:
by using a convex lens?
An eye has a far point of 2 m. What type of lens in spectacles would be needed to increase the far point to infinity? Also calculate the power of lens required. Is this eye long-sighted or short-sighted?
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
Name the following:
The photosensitive pigment present in the rods of the retina.
Given below is a diagram depicting a defect of the human eye. Study the same and answer the question that follow:
Name the defect shown in the diagram.
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?
Given alongside is a diagram depicting a defect of the human eye. Study the same and then answer the questions that follow:
- Identify the defect.
- Name the parts labelled 1, 2 and 3.
- Give two possible reasons for this eye defect.
- Draw a labelled diagram to show how the above mentioned defect is rectified.
Given below is a diagram depicting a defect of the human eye? Study the same and answer the question that follow:
Give two possible reasons for this defect of the eye in human beings.
The near point of the eye of a person is 50 cm. Find the nature and power of the corrective lens required by the person to enable him to see clearly the objects placed at 25 cm from the eye?
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.
Differentiate between:
Short-sightedness and Long-sightedness.
What type of lens is used to correct Astigmatism?
Due to elongation of _______ and increase in curvature of the eye lens, a person cannot see distant objects clearly.
Observe the given below the figure, correct it and explain and write about the concept depicted in this figure.
Which of the following statement is correct?
A person is unable to see clearly a poster fixed on a distant wall. He however sees it clearly when standing at a distance of about 2 m from the wall.
- Draw ray diagram to show the formation of image by his eye lens when he is far away from the wall.
- List two possible reasons of this defect of vision.
- Draw ray diagram to show the correction of this defect using appropriate lens.
