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The radii of curvature of a lens are +20 cm and +30 cm. The material of the lens has a refracting index 1.6. Find the focal length of the lens
(a) If it is placed in air, and
(b) If it is placed in water (μ = 1.33).
Radii of curvature of a lens are:
Refractive index of material == 1.6
Refractive index of water = = 1.33
(a) When lens is placed in air
By using the lens makers’ formula;
We get;
(b) If it is placed in water (μ = 1.33).
By using the lens makers’ formula;
we get;