Question:
Find the distance of the image from object $\mathrm{O}$, formed by the combination of lenses in the figure :
Correct Option: 1
Solution:
$\frac{1}{V_{1}}+\frac{1}{30}=\frac{1}{10}$
$\frac{1}{V_{1}}=\frac{2}{30} \Rightarrow V_{1}=15 \mathrm{~cm}$
$\frac{1}{\mathrm{~V}_{2}}-\frac{1}{10}=-\frac{1}{10}$
$\frac{1}{\mathrm{~V}_{2}}=0 \quad \mathrm{~V}_{2}=\infty$
$\mathrm{V}_{3}=30 \mathrm{~cm}$
$\mathrm{OV}_{3}=75 \mathrm{~cm}$