Question

If yellow light emitted by sodium lamp in Young's double slit expt is replaced by monochromatic blue of light of the same intensity

• A. fringe width will decrease
• B. fringe width will increase
• C. fringe width will remain unchanged
• D. fringes will becomes less intense

Answer 1

Answer: (A)

fringe width will decrease

Answer 2

As $\beta = \frac{\lambda D }{d} \, \, and \, \, {\lambda}_b < {\lambda}_y ,$
$\therefore \, \, \,$ Fringe width $\beta$ will decrease