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MHT CET · Physics · Wave Optics

In biprism experiment, 21 fringes are observed in a given region using light of wavelength \(480 Å\). If light of wavelength \(560 Å\) is used, the number of fringes in the same region will be

  1. A 18
  2. B 24
  3. C 14
  4. D 21
Verified Solution

Answer & Solution

Correct Answer

(A) 18

Step-by-step Solution

Detailed explanation

\(
\mathrm{n}_1 \beta_1=\mathrm{n}_2 \beta_2
\)
\(
21 \times \frac{\lambda_1 \mathrm{D}}{\mathrm{d}}=\mathrm{n}_2 \times \frac{\lambda_2 \mathrm{D}}{\mathrm{d}}
\)
\(
\mathrm{n}_2=21 \times \frac{\lambda_1}{\lambda_2}=\frac{21 \times 480}{560}=18
\)