Young's double slit experiment is carried out by using green, yellow, red and blue lights one by one. Arrange the expected values of fringe width \( (\beta) \) in increasing order
(A) \( \beta_{\mathrm{Green}} \)
(B) \( \beta_{\mathrm{Yellow}} \)
(C) \( \beta_{\mathrm{Blue}} \)
(D) \( \beta_{\mathrm{Red}} \)
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (C), (A), (B), (D)
The fringe width in Young's experiment is proportional to the wavelength of the light used.
\( \displaystyle \beta = \frac{\lambda D}{d} \;\Rightarrow\; \beta \propto \lambda \)
The wavelengths of the four colours increase in the order blue, green, yellow, red. So the fringe widths increase in the same order.
\( (C)\ \beta_{\mathrm{Blue}} \lt (A)\ \beta_{\mathrm{Green}} \lt (B)\ \beta_{\mathrm{Yellow}} \lt (D)\ \beta_{\mathrm{Red}} \)
The order is C, A, B, D.