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 (i) distant vision, and (ii) near vision?

A person needs a lens of power - 5.5 dioptres for correcting his dista

1.	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 (i) distant vision, and (ii) near vision?
Answer» <P> Solution :(i) For distant VISION `P=-5.5D` `f=(1)/(P)=(1)/(-5.5)=-0.182m` `f=-18.2cm` (II) For distant vision `P=1.5D` `f=(1)/(P)=(1)/(1.5)=0.667m` `f=66.7cm`