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 :

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 : (A) 10 Cm (B) 40 Cm (C) 30 Cm (D) 50 Cm

Tardigrade Admin · Accepted Answer

(1/ v )-(1/ u )=(1/ f ) P =2 D =2 m -1 ⇒ (1/ f )=(2/100) cm -1 (1/ V )-(-(1/25))=(2/100) ⇒ (1/ V )=(1/50)-(1/25) ⇒ V =-50 cm

Q. 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 :

10 Cm

40 Cm

30 Cm

50 Cm

$\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$
$P = 2 D = 2 m^{- 1}$
$\Rightarrow \frac{1}{f} = \frac{2}{100} c m^{- 1}$
$\frac{1}{V} - (- \frac{1}{25}) = \frac{2}{100}$
$\Rightarrow \frac{1}{V} = \frac{1}{50} - \frac{1}{25}$
$\Rightarrow V = - 50 c m$

Q. 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 :