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प्रश्न
Explain the Term: Astigmatism
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उत्तर
Astigmatism: It is a defect in which some parts of the object are seen in focus while others are blurred. It arises due to the uneven curvature of the cornea. This is corrected by cylindrical lenses.
संबंधित 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?
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.
Draw a ray diagram to show how Hypermetropia is defect can be corrected using a lens.
State the main functions of the following:
Tears
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?
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?
Mention, if the following statement is True or False
Hypermetropia is a defect of the eye caused due to the eyeball elongation
A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power:
Draw ray diagram showing myopic eye.
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.
