A concave lens has same radii of curvature for both sides and is made of material of refractive in index `1.6` It is immersed in a liquid of `mu = 1.4` Calculate ratio of focal lengths of lens in air and liquid.

Answer

`0.238`

Explanation

Use `(1)/(f_a) = ((mu_g)/(mu_a) - 1) ((1)/(R_1) - (1)/(R_2))`
and `(1)/(f_1) = ((mu_g)/(mu_l) - 1) ((1)/(R_1) - (1)/(R_2))`.