JEE Mains · Physics · STD 12 - Ray optics and optical instruments
- JEE Mains 2014
- Medium
- MCQ
A thin convex lens made from crown glass \(\left( {\mu = \frac{3}{2}} \right)\) has focal length \(f\). When it is measured in two different liquids having refractive indices \(\frac{4}{3}\) and \(\frac{5}{3}\) it has the focal lengths \(f_1\) and \(f_2\) respectively. The correct relation between the focal lengths is:
Pick an option to check your answer.
Answer & Solution
Correct Answer
(A) \(f_1 > f \) and \(f_2\) becomes negative
Step-by-step Solution
Detailed explanation
By Lens maker's formula for convex lens
\(\frac{1}{f}=\left(\frac{\mu}{\mu_{L}}-1\right)\left(\frac{2}{R}\right)\)
for, \(\mu_{L_{1}}=\frac{4}{3}, f_{1}=4 R\)
for \(\mu_{L_{2}}=\frac{5}{3}, f_{2}=-5 R\)
\(\Rightarrow f_{2}=(-) \mathrm{ve}\)
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