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 $|f_{\text{convex}}| > |f_{\text{concave}}|$
$\dfrac{1}{F} = \dfrac{1}{|f_{\text{convex}}|} - \dfrac{1}{|f_{\text{concave}}|}$.
If $|f_{\text{convex}}| > |f_{\text{concave}}|$, the concave lens is stronger, $F < 0$, and the combination is diverging. Swapping thin lenses in contact changes nothing.
Solution by Sreeraj P, M.Sc Physics