Question

In Young’s double slit experiment, what should be the phase difference between the two overlapping waves to obtain 5th dark band/fringe on the screen?

Answer 1

For dark band path difference

P = (2m - 1)`lambda/2`

Here m = 5

P = `(2 xx 5 - 1)lambda/2 = (9lambda)/2`

∴ Phase difference = `(2pi)/lambda xx "p"`

`= (cancel(2)pi)/cancel(lambda) xx (9cancel(lambda))/cancel(2)`

= 9 π