Question

Ques:-A person needs a lens of power -5.5 dioptres for correcting his distant vision. For correcting his near vision he needs a lens of power +1.5 dioptre. What is the focal length of the lens required for correcting distant vision?

Answer 1

first of the power is

-5.5D

so,

1/f=p

1/p=f ( in cm)

100/-5.5 =f

f=-18.18 cm

If the power is +1.5 Dioptre

100/1.5=f

f=66.66 cm