A convex lens of focal length f and dispersive power w is

Last updated: 6/25/2023

A convex lens of focal length f and dispersive power w is combined with a concave lens of focal length f2 and dispersive power 02 is such a way that an achromatic doublet of focal length 40 cm is obtained If respectively 40 3 1 2 20 3 40 3 4 20 20 40 3 20 40 2 W2 3 then f and f2 in cm are