ExamBro
ExamBro
MHT CET · Physics · Ray Optics

A convex lens is dipped in a liquid whose refractive index is equal to refractive index of lens material. Then its focal length will

  1. A become infinite
  2. B remain same
  3. C decrease
  4. D become zero
Verified Solution

Answer & Solution

Correct Answer

(A) become infinite

Step-by-step Solution

Detailed explanation

Given that refractive of liquid is equal to refractive index of lens.
\(\Rightarrow n_{\text {lens }}=n_{\text {liquid }}\)
Let the focal length be \(f\).
From lens makers formula, we get \(\frac{1}{f}=\frac{\left(n_{\text {lens }}-n_{\text {liquid }}\right)}{n_{\text {liquid }}}\left(\frac{1}{R_1}-\frac{1}{R_2}\right)\)
Here, \(n_{\{\text {lens }\}}-n_{\{\text {liquid }\}}=0\)
Therefore, the focal length will be infinite.