A lens has radii of curvature of +20 cm and +30 cm . The material of the lens has a refracting index of 1.6 . Determine the focal length of the lens when it is placed in air.

Step-by-step solution

Using the Lens Maker's formula: 1 f = ( - 1) ( 1 R₁ - 1 R₂ ) Given R₁ = +20 cm , R₂ = +30 cm , and = 1.6 . Substituting the values: 1 f = (1.6 - 1) ( 1 20 - 1 30 ) 1 f = 0.6 ( 3 - 2 60 ) 1 f = 0.6 1 60 1 f = 1 100 f = +100 cm