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प्रश्न
Give Reason:
Deficiency of vitamin A causes night blindness.
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उत्तर
Because the visual purple (Rhodopsin) of the rods is not formed in the absence of vitamin A.
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संबंधित प्रश्न
Explain two possible reasons of myopia. How can it be corrected? Explain with a suitable diagram.
What is the other name for
myopia
What is the other name for
hypermetropia
A short-sighted person has a near point of 15 cm and a far point of 40 cm.
(a) Can he see clearly an object at a distance of:
(i) 5 cm?
(ii) 25 cm?
(iii) 50 cm?
(b) To see clearly an object at infinity, what kind of spectacle lenses does he need?
The near point of a long-sighted person is 50 cm from the eye.
(a) Can she see clearly an object at:
(i) a distance of 20 cm?
(ii) at infinity?
You do not enjoy watching a movie from a very short distance from the screen in a cinema hall. Why?
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.
Choose the Odd One Out:
Differentiate the eye defects: Myopia and Hypermetropia
Assertion: Concave mirrors are used as reflectors in torches, vehicle head lights and in search lights.
Reason: When an object is placed beyond the center of curvature of a concave mirror, the image formed is real and inverted.
