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In the given figure, the radius of curvature of curved surface for both the plano-convex and plano-concave lens is 10 cm and refractiveindex for both is 1.5. The location of the final image after all the refractions through lenses is |
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Answer» Solution :The focal length of the plano-convex lens is `1/f = (1.5-1)(1/(+10)- (1)/(oo)) = 1/20` Focal length of plano-concave lens is `1/f =(1.5-1) (1/oo - 1/10) = (-1)/(20)` SINCE parallel beams are incident on the lens, its image from plano-concave lens will be formed at `+20` cm from it (at the FORCUS) and will act as an object for the plano-concave lens. Since the two lens are at a distance of `10 cm` fromeach other, therefore, cor the next lens`u= +10cm`. `:.V = (uf)/(u+f) = (10 xx 20)/(10 - 20) = 20 cm` |
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