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प्रश्न
Explain with the help of labelled ray diagram, the defect of vision called myopia and how it is corrected by a lens.
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उत्तर
Myopia is a defect of vision because of which a person is unable to see distant objects clearly but has normal near vision. Myopia occurs because the converging power of the eye lens is greater than normal and the images of distant objects are formed in front of the retina. As a result, a person with myopia cannot see these objects clearly. In certain other cases, myopia occurs because the eyeball is too long and the distance of the retina from the eye lens is large. This, too, causes the formation of images in front of the retina. The far point of a myopic eye is closer than infinity. The following ray diagram explains the myopic eye and how the defect can be corrected by using concave lenses. A concave lens diverges the light rays from distant objects to form virtual images of the objects at the far point of eye. The eye lens then easily focusses the light rays from the far point to form clear images on the retina.
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संबंधित प्रश्न
the biological/technical terms for the lens of eye losing flexibility resulting in a kind of long-sightedness in middle aged people.
A student is unable to see clearly the words written on the black board placed at a distance of approximately 3 m from him. Name the defect of vision the boy is suffering from. State the possible causes of this defect and explain the method of correcting it.
What is the other name for
myopia
Name the defect of vision in which the eye-lens loses its power of accommodation due to old age.
Name the body part with which the terms myopia and hypermetropia are connected.
Your friend can read a book perfectly well but cannot read the writing on blackboard unless she sits on the front row in class.
What type of lenses-converging or diverging-would an optician prescribe for her?
Differentiate between myopia and hypermetropia. What type of spectacles should be worn by a person having the defects of myopia as well as hypermetropia? How does it help?
What eye defect is hypermetropia? Describe with a ray diagram how this defect of vision can be corrected by using an appropriate lens.
Distinguish between the following pair of words:
Myopia and hypermetropia
Given alongside is a diagram depicting a defect of the human eye. Study the same and then answer the questions that follow:
(i) Identify the defect.
(ii) Name the parts labelled 1, 2 and 3.
(iii) Give labelled two possible reasons for this eye defect.
(iv) Draw a labelled diagram to show how the above mentioned defect is rectified.
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?
Give Reason:
Older people require glasses to read and write.
Give Reason:
When you enter into a dark room from bright because of sunlight, you can not see things for a few seconds.
Differentiate between:
Short-sightedness and Long-sightedness.
In Myopia the human eye _______.
A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power:
Which of the following statement is correct?
Which of the following statement is correct?
Name the following:
Two kinds of accomodations.
Given alongside is a diagram depicting a defect of the human eye. Study the same and answer the questions that follow:
 |
- Name the defect shown in the diagram.
- Give two possible reasons for this defect.
- Name the parts labelled 1 to 4.
- Name the type of lens used to correct this eye defect.
- Draw a labelled diagram to show how the above mentioned defect is rectified using the lens named above.
