Double convex lenses are to be manufactured from a glass of refractive index 1.55, with both faces of same radius of curvature. What is the radius of curvature required if the focal length is to be 20 cm?
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Updated on : 2022-09-05
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Correct option is B)
Lens maker's formula, f1=(μ−1)(R11−R21) Here, f = 20 cm, μ = 1.55, R1 = R, R2 = -R 201=(1.55−1)(R1−(−R)1)or201=0.55×R2 ⇒R=1.1×20=22cm
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