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Question
The near point of a long-sighted person is 50 cm from the eye.
- Can she see clearly an object at:
- a distance of 20 cm?
- at infinity?
- To read a book held at a distance of 25 cm, will she need converging or diverging spectacle lenses?
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Solution
-
- A long-sighted person who has a near point of 50 cm from the eye cannot clearly see an object kept at a distance of 20 cm. She can see an object only if it is kept at her near point of 50 cm in front of the eye.
- As the person is long-sighted, she cannot see nearby objects, but can see distant objects clearly. Therefore, she can clearly see the object kept at infinity.
- To read a book held at a distance of 25 cm, the person, who is long-sighted, will need converging lenses.
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