Question 153: 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: