Q. The combination of a convex lens $(f = 18\ cm)$ and a thin concave lens $(f = 9\ cm)$ is
A) A concave lens $(f = 18\ cm)$
B) A convex lens $(f = 18\ cm)$
C) A convex lens $(f = 6\ cm)$
D) A concave lens $(f = 6\ cm)$
Explanation
(a) $\frac{1}{F} = \frac{1}{+ 18} + \frac{1}{( - 19)} \Rightarrow F = - 18\ cm\ (i.e.,\ $concave lens)
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.