A certain far – sighted person cannot see object that are closer to the eye than 50 cm clearly. Determine the power of the converging lens which will enable him to see at 25 cm

A. 0.06 D
B. 0.02 D
C. 0.03 D
D. 0.04 D
E. no option is correct

Correct Answer:

Option E – no option is correct

Explanation

V = – 50, U = 25CM
(1)/r = (1)/v + (1)/u = (1)/-50 + (1)/25 = (1 + 2)/50 = (1)/50 f = +50cm = +0.5m
p = (1)/r = (1)/0.5 = (10)/5 = 2 diopters
The power of a lens is the reciprocal of the focal length in meters. it is expressed in diopters.