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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
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.
Though a woman can see the distant object clearly, she cannot see the nearby objects clearly. She is suffering from the defect of vision called:
(a) long-sight
(b) short-sight
(c) hind-sight
(d) mid-sight
Differentiate between members of the following pair with reference to what is asked in bracket.
Myopia and hyperopia (cause of the defect)
Name an old age eye defect. What happens in it?
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?
Due to elongation of _______ and increase in curvature of the eye lens, a person cannot see distant objects clearly.
Nearsightedness : concave lens : : farsightedness : _______
A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power:
A teacher drew the diagram of the heart on the blackboard and told the students to copy it in their notebooks. Mahesh couldn't see the diagram clearly as it appeared blurred to him.
- Name the defect of the eye Mahesh is suffering from.
- Where is the image formed in this defect?
- Mahesh consults an eye doctor and is prescribed suitable lenses to correct the defect. Which type of lens do his spectacles have?
Name the following:
Two kinds of accomodations.
