JEE Mains · Physics · STD 12 - 9. Ray optics and optical instruments
A convex lens made of glass (refractive index \(=1.5\) ) has focal length 24 cm in air. When it is totally immersed in water (refractive index \(=1.33\) ), its focal length changes to ________.
- A 24 cm
- B 96 cm
- C 48 cm
- D 72 cm
Answer & Solution
Correct Answer
(B) 96 cm
Step-by-step Solution
Detailed explanation
\begin{aligned} & \frac{1}{8}=\left(\frac{\mu_{\ell}}{\mu_{\mathrm{s}}}-1\right)\left[\frac{1}{\mathrm{R}_1}-\frac{1}{\mathrm{R}_2}\right] \\ & \frac{1}{24}=(1.5-1)\left[\frac{2}{\mathrm{R}}\right] ...(i)\\ &…
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