If $f_{V}$ and $f_{R}$ are the focal lengths of a convex lens for violet and red light respectively

Question

If $f_{V}$ and $f_{R}$ are the focal lengths of a convex lens for violet and red light respectively and $F_{V}$ and $F_{R}$ are the focal lengths of a concave lens for violet and red light respectively, then we must have\

Professor PC Thomas Classes · Answer

(b) : For a convex lens, $f_{R}>f_{V}$ or $f_{V}F_{R}$ as the smaller negative value is bigger.\