A concave-convex lens of refractive index 1.5 and the radii of curvature of its surfaces are 30 cm and 20 cm , respectively. The concave surface is upwards and is filled with a liquid of refractive in

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A concave-convex lens of refractive index 1.5 and the radii of curvature of its surfaces are 30 cm and 20 cm , respectively. The concave surface is upwards and is filled with a liquid of refractive index 1.3. The focal length of the liquid-glass combination will be

TestHub · Accepted Answer

f 1 ​ f ​ = ( 1 1.3 − 1 ​ ) ( ∞ 1 ​ − − 30 1 ​ ) = ( 1 1.5 − 1 ​ ) ( − 30 1 ​ − − 30 1 ​ ) = 30 0.3 ​ + 60 0.5 ​ = 100 1 ​ + 120 1 ​ = 600 6 + 5 ​ = 600 11 ​ = 11 600 ​ cm ​

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