V.K. Sally Solutions for Chapter: Human Eye and Colourful World, Exercise 1: Practice Problems : 1

The power of a lens for distant vision for a nearsighted person is $-3.5 \mathrm{D}$. If a correction of $+1.0 \mathrm{D}$ is required in his bifocal lens, in order to see near objects, calculate focal length for distant vision.

The power of a lens for a distant vision for a nearsighted person is $-3.5 \mathrm{D}$. If a correction of $+1.0 \mathrm{D}$ is required in his bifocal lens, in order to see near objects, calculate the focal length for near vision.

A near-sighted person wears eyeglasses of power $-4.5 \mathrm{D}$ for distant vision. His doctor prescribes a correction of $+0.75 \mathrm{D}$ in near vision section of his bifocals, which measured relative to main part of the lens. What is the focal length of his distant viewing part of the lens?

A near-sighted person wears eyeglasses of power $-4.5 \mathrm{D}$ for distant vision. His doctor prescribes a correction of $+0.75 \mathrm{D}$ in near vision section of his bifocals, which measured relative to main part of the lens. What is the focal length of his near viewing section of the lens?