The distance of distinct vision of a person is 50 cm. He wants to read a book placed at 25 CM. What should be the focal length of the spectacles ?

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Solution

v=-50cm
u=-25cm(normal near point)
focal length=?
Lens formula:
1/f=1/v-1/u
1/f=1/-50 -1/-25
=1/25-1/50
=2-1/50=1/50
f=50cm
focal length 50cm

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The distance of distinct vision of a person is 50 cm. He wants to read a book placed at 25 CM. What should be the focal length of the spectacles ?

v=-50cm u=-25cm(normal near point) focal length=? Lens formula: 1/f=1/v-1/u 1/f=1/-50 -1/-25 =1/25-1/50 =2-1/50=1/50 f=50cm focal length 50cm

v=-50cm
u=-25cm(normal near point)
focal length=?
Lens formula:
1/f=1/v-1/u
1/f=1/-50 -1/-25
=1/25-1/50
=2-1/50=1/50
f=50cm
focal length 50cm