Two identical glass \((\mu_g = 3/2)\) equiconvex lenses of focal length \(f\) each are kept in contact. The space between the two lenses is filled with water \((\mu_w = 4/3).\) The focal length of the combination is

A \(\frac{{4f}}{3}\)
B \(\;\frac{{3f}}{4}\)
C \(\;\frac{f}{3}\)
D \(f\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(\;\frac{{3f}}{4}\)

Step-by-step Solution

Detailed explanation

\(\text { Here, } \mu_{g}=\frac{3}{2}, \mu_{w}=\frac{4}{3}\) Focal length \((f)\) of glass convex lens is given by

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

Explore more questions on app

From NEET

Match List-I with List-II

List-I (Electromagnetic wave)	List-II (Production)
(A) Microwave	(I) Electrons in atoms emit light when they move from a higher energy level to a lower energy level
(B) Visible light	(II) Radioactive decay of nucleus
(C) Gamma rays	(III) Vibration of atoms and molecules
(D) Infra-red rays	(IV) Klystron valve or magnetron valve

Choose the correct answer from the options given below:

NEET 2026 Easy

Explore more questions on app