Question

A person who can see distinctly from a distance of 1 metre wants to read. A book

Answer 1

distance of the near point, x' = 100cm

power of the lens, P = ?

focal length of the lens, f = ?

So the focal length, f = x'×d / x'- d

= 100 ×25 / 100 - 25

= 100 × 25 / 75

f = 100 / 3 cm

So the power of a lens, P = 1/f(m)

= 100/100/3

or,. = 3/1

P = 3 D