Question

The near point of an elderly person is 50
cm from the eye, then the focal length and
power of the corrective lens that will correct
his vision is:
A
2 cm, 5 D
B
50 cm, 2 D
С
100 cm, 1 D.
D
200 cm, 0.5 D​

Answer 1

Answer:

after applying the lens formula 1/f = 1/v - 1/u

v = -50 cm

u = - 25 cm

1/f = -1/50 + 1/25

1/f = 1/50

f = 50 cm

now the power of lens is 100/50 = +2 D

the lens use concave lens because the power of the lens is positive

hope this helps love