JEE Mains · Physics · STD 12 - 9. Ray optics and optical instruments
For the thin convex lens, the radii of curvature are at \(15 \mathrm{~cm}\) and \(30 \mathrm{~cm}\) respectively. The focal length the lens is \(20 \mathrm{~cm}\). The refractive index of the material is _______.
- A \(1.2\)
- B \(1.4\)
- C \(1.5\)
- D \(1.8\)
Answer & Solution
Correct Answer
(C) \(1.5\)
Step-by-step Solution
Detailed explanation
\(\frac{1}{\mathrm{f}}=\left(\frac{\mu_{\mathrm{ears}}}{\mu_{\mathrm{alr}}}-1\right)\left(\frac{1}{\mathrm{R}_1}-\frac{1}{\mathrm{R}_2}\right)\) \(\Rightarrow \frac{1}{+20}=\left(\frac{\mu}{1}-1\right)\left(\frac{1}{+15}-\frac{1}{(-30)}\right)\)…
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