Question

A man can read a book placed at 20 m . If the book is kept at a distance of 30 m. he has to use a spectacles .
calculate 1. focal length
2. nature of lens​

Answer 1

Answer:

Given, u = -20 cm, v = - 30 cm , P = ?

f = uv/u-v = (-20)(-30)/(-20+30)

f = +60cm

P = 100/f = 100/60

P = 1.67 D

Step-by-step explanation:

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