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COMEDK · Physics · 25. Ray Optics

Newton's rings are observed normally in reflected light of wavelength \(5000 Å\). The diameter of the 10 th dark ring is \(0.005 \mathrm{~m}\). The radius of curvature of the lens is

  1. A \(1 \mathrm{~m}\)
  2. B \(1.25 \mathrm{~m}\)
  3. C \(2 \mathrm{~m}\)
  4. D \(0.5 \mathrm{~m}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(1.25 \mathrm{~m}\)

Step-by-step Solution

Detailed explanation

In Newton's ring experiment, diameter of \(n\)th dark ring, \(D_{n}=2 \sqrt{n \lambda R}\) \(\Rightarrow\) \(R=\frac{D_{n}^{2}}{4 n \lambda}\) ...(i) Given, \(n=10, D_{10}=0.005 \mathrm{~m}\) \(\lambda=5000 Å=5 \times 10^{-7} \mathrm{~m}\) \(\therefore\) Putting these values in…