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प्रश्न
What are the causes of ‘Myopia’?
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उत्तर
Myopia, also known as short-sightedness, occurs due to the lengthening of the eyeball. With this defect, nearby objects can be seen clearly but distant objects cannot be seen clearly.
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संबंधित प्रश्न
Do you know that the corneal-impairment can be cured by replacing the defective cornea with the cornea of the donated eye? How and why should we organise groups to motivate the community members to donate their eyes after death?
Which defect of vision can be rectified:
by using a concave lens?
Which defect of vision can be rectified:
by using a convex lens?
Explain the terms ‘adaptation’ and ‘accommodation’ with reference to the eye.
Draw a ray diagram to show how Hypermetropia is defect can be corrected using a lens.
A person is unable to see objects distinctly placed within 50 cm from his eyes.
(a) Name the defect of vision the person is suffering from and list its two possible causes.
(b) Draw a ray diagram to show the defect in the above case.
(c) Mention the type of lens used by him for the correction of the defect and calculate its power. Assume that the near point for the normal eye is 25 cm.
(d) Draw a labeled diagram for the correction of the defect in the above case.
Explain the Term: Presbyopia
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.
Myopia may arise due to ____________.
A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard. What advice will a doctor give to her? Draw ray diagram for the correction of this defect.
