A double convex thin lens made of refractive index 1.6 has radii of curvature 15 cm each. The focal length of this lens when immersed in a fluid of refractive index 1.63, is

Question

Dr. Abubacker · Accepted Answer

(d) Focal length of lens in given by
$\frac{1}{f_{w}} = \ \left( \mu_{g} - 1 ight)\left( \frac{1}{R_{1}} - \frac{1}{R_{2}} ight)$
$= \left( \frac{1.6}{1.63} - 1 ight)\left( \frac{1}{15} + \frac{1}{15} ight)$
$= - \frac{0.03 	imes 2}{1.63 	imes 15} = \frac{- 6}{1.63 	imes 15}$
$so,\ \ f_{w} = \  - \frac{815}{2}$
$= - 407.5\ cm$

Q. A double convex thin lens made of refractive index 1.6 has radii of curvature 15 cm each. The focal length of this lens when immersed in a fluid of refractive index 1.63, is

Explanation

Reviewed by Dr. Abubacker

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