Question 99: Ray Optics

Question

A person has been using spectacles of power $-1.0$ dioptre for distant vision and a separate reading glass of power $2.0$ dioptres. What is the least distance of distinct vision for this person :

Accepted Answer

u = 25 cm
$f=\frac{1}{2}$ m = 50 cm
${1 \over v} - {1 \over u} = {1 \over f}$
$ \Rightarrow {1 \over v} + {1 \over {25}} =  - {1 \over {50}}$
${1 \over v} =  - {1 \over {50}}$
$ \Rightarrow u =  - 50$ cm

Answer

50 cm

Answer

40 cm

Answer

30 cm

Answer

10 cm

Ray Optics

A person has been using spectacles of power -1.0 dioptre for distant vision and a separate reading glass of power 2.0 dioptres. What is the least distance of distinct vision for this person :

Choose the correct answer: