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प्रश्न
Give Reason:
Older people require glasses to read and write.
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उत्तर
In old age the flexibility of the lens declines and the lens becomes less convex or opaque leading to weakness of eyesight.
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संबंधित प्रश्न
What is the far point and near point of the human eye with normal vision?
What is the other name of old age hypermetropia?
What is meant by optical illusion? Give one example.
By closing the eyes and gently pressing them by your palms, you may see some specks of brilliant light. How do you get this sensation while there is no light entering your eyes?
Write whether the following is true or false:
A convex lens is used for correcting myopia.
The diagram alongside represents a section of a mammalian eye.
(i) Label the parts 1 to 5 of the diagram.
(ii) State the function of the parts labelled 4 and 5.
(iii) With the help of a diagram show the short sightedness.
With respect to human eye explain:
(i) How is the image formed on the retina?
(ii) How is the amount of light entering the eye-controlled?
(iii) What type of lens is used for the correction of ‘Long sight’ defect?
(iv) With the help of a ray, diagram show the defect of the eye and then its correction after the use of a lens.
Given below is a diagram showing a defect of vision. Name the defect of vision and draw an accurately labelled diagram to correct this defect.
A person needs a lens of power –4.5 D for correction of her vision.
- What kind of defect in vision is she suffering from?
- What is the focal length of the corrective lens?
- What is the nature of the corrective lens?
Observe the figure whether it is correct or not and explain the phenomenon.
