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प्रश्न
Differentiate between members of the following pair with reference to what is asked in the bracket.
Rods and cones (sensitivity).
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उत्तर
Rods: They are sensitive to dim light but do not respond to colour.
Cones: They are sensitive to bright light and are responsible for colour vision.
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संबंधित प्रश्न
Given below is a diagram showing a defect of human eye. Study it and answer the following questions.
(i) Name the defect shown in the figure.
(ii) Give reason for this defect of eye in human being.
(iii) Name the type of lens used to correct the eye defect.
What is myopia?
List three common refractive defects of vision. Suggest the way of correcting these defects.
Name the defect of vision in which the eye-lens loses its power of accommodation due to old age.
The near-point of a person suffering from hypermetropia is at 50 cm from his eye. What is the nature and power of the lens needed to correct this defect? (Assume that the near-point of the normal eye is 25 cm).
A person can read a book clearly only if he holds it at an arm's length from him. Name the defect of vision:
- if the person is an old man
- if the person is a young man
Have a look at the posture of this woman who is reading a book and answer the questions which follow:
What are the two conditions shown in sections A and B of the eye as applicable to her?
Have a look at the posture of this woman who is reading a book and answer the questions which follow:
What kind of looking glasses she needs?
What type of lens is used to correct Astigmatism?
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.
