Optics Question 695

Question: A thin glass (refractive index 1.5) lens has optical power of $ -5D $ in air. It’s optical power in a liquid medium with refractive index 1.6 will be

[AIEEE 2005]

Options:

A) 25 D

B) ? 25 D

C) 1 D

D) None of these

Show Answer

Answer:

Correct Answer: D

Solution:

$ \frac{f _{l}}{f _{a}}=\frac{{( _{a}}{\mu _{g}}-1)}{{( _{l}}{\mu _{g}}-1)} $

Therefore $ \frac{f _{l}}{f _{a}}=\frac{ _{a}{\mu _{g}}-1}{ _{l}{\mu _{g}}-1}=\frac{1.5-1}{\frac{1.5}{1.6}-1}=\frac{0.5\times 1.6}{-0.1}=-8 $

Therefore $ P _{l}=\frac{P _{a}}{8}=\frac{5}{8} $



NCERT Chapter Video Solution

Dual Pane