The radii of curvature R_(1) and R_(2) of an equiconvex lens is each 20 cm and the refractive index of the material is 1.5. Its focal length will be _________.

The radii of curvature R_(1) and R_(2) of an equiconvex lens is each 2

1.	The radii of curvature R_(1) and R_(2) of an equiconvex lens is each 20 cm and the refractive index of the material is 1.5. Its focal length will be _________.
Answer» SOLUTION :Hint : Here `R_(1)=+20 CM, R_(2)=-20 cm and N = 1.5` `therefore (1)/(f)=(n-1)((1)/(R_(1))-(1)/(R_(2)))=(1.5-1)[(1)/((+20))-(1)/((-20))]=(1)/(20) or f=20cm`

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The radii of curvature R_(1) and R_(2) of an equiconvex lens is each 20 cm and the refractive index of the material is 1.5. Its focal length will be _________.

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