JEE Mains · Physics · STD 12 - 9. Ray optics and optical instruments
A lens having refractive index 1.6 has focal length of 12 cm , when it is in air. Find the focal length of the lens when it is placed in water.
(Take refractive index of water as 1.28)
- A 355 mm
- B 288 mm
- C 555 mm
- D 655 mm
Answer & Solution
Correct Answer
(B) 288 mm
Step-by-step Solution
Detailed explanation
As we know, \(\frac{1}{\mathrm{f}}=\left[\frac{\mu_{\mathrm{L}}}{\mu_{\mathrm{m}}}-1\right]\left[\frac{1}{\mathrm{R}_1}-\frac{1}{\mathrm{R}_2}\right]\) For air \(\mu_{\mathrm{m}}=1\)…
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