In YDSE when a point source S1 of monochromatic light of wavelength λ1 is used the number of bright fringes obtained on the screen is n1. If the point source S1 is replaced by another point source S2 of monochromatic light of wavelength λ2(λ2< λ1 ), the number of bright fringes obtained on the screen is n2, then
Answer & explanation
Correct answer: option 2
$\text{Let width of screen is L} $
$ n_1 = \frac{L}{\beta_1} = \frac{L}{\lambda_1 D/d} = \frac{dL}{\lambda_1 D}$
$ n_2 = \frac{L}{\beta_2} = \frac{L}{\lambda_2 D/d} = \frac{dL}{\lambda_2 D}$
$ \text{Since } \lambda_1 > \lambda_2$
$ \Rightarrow n_2 \ge n_1$