Q 12-09-045JEE MainJEE Main 2026 (5 Apr, Shift 2)Easy
A thin convex lens and a thin concave lens are kept in contact and are co-axial. Which of the following statements is correct for this combination of two lenses ?
Answer: (A) behaves as concave lens if $|f_{\text{convex}}| > |f_{\text{concave}}|$
Concept. Thin lenses in contact: $P=P_1+P_2=\dfrac1{|f_{convex}|}-\dfrac1{|f_{concave}|}$.
Step 1. Sign of the total. If $|f_{convex}|>|f_{concave}|$, the concave lens has the larger power, so $P\lt0$: the pair acts as a concave lens.
Step 2. Other options. B and C are the reverse of this; D is false because the sum of powers does not depend on order.
Answer. Option A.
Solution by Sreeraj P, M.Sc Physics
