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प्रश्न
Given below is a diagrammatic representation of a defect of the human eye:
(i) Identify the defect.
(ii) Mention two reasons for the above defect.
(iii) State how the defect can be rectified.
(iv) Name the part of the eye responsible for maintaining the shape of the eyeball.
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उत्तर
(i) Hypermetropia (Far-sightedness) because the image is behind the retina.
(ii) Reasons for hypermetropia are:
1. Shortening of the eyeball from front to back.
2. The lens becomes too flat.
(iii) It can be rectified by using convex lenses of appropriate power (focal length).
(iv) Sclerotic (or sclera).
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संबंधित प्रश्न
Name one defect of vision (or eye) which cannot be corrected by any type of spectacle lenses.
Name the defect of vision which can be corrected by a diverging lens. Show clearly by a ray diagram how the lens corrects the defect.
A person suffering from the eye-defect myopia (short-sightedness) can see clearly only up to a distance of 2 metres. What is the nature and power of lens required to rectify this defect?
Name the following:
The eye defect caused due to shortening of the eye ball from front to back.
What is meant by optical illusion? Give one example.
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.
Observer the following diagram and answer the questions.
a) Which eye defect is shown in this diagram?
b) What are the possible reasons for this eye defect?
c) How this defect is corrected, write it in brief?
Choose the correct answer :
Presbyopia is a disease of _____________
Complete the following sentence with appropriate word :
An inability to focus on nearby objects due to loss of elasticity of the lens with age is called Iris.
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.
