Question

The near point of a long-sighted person is 200 cm. What should be power of his spectacle
to read a book kept 25 cm away?
| (A) -2.5 D
| (B) +1.5 D
(C) - 3.5 D
(D) + 3.5 D.
​

Answer 1

Explanation:

u= -25cm

v= -200cm

f=?

now, 1/V-1/U =1/F

1/-200-1/_25 =1/F

-1+8/200=1/F

200/7 = F

F = 28.57 cm

AS F IS POSITIVE SO THE LENS IS CONVRX