Two points nonochromatic and coherent sources of light of wavelength `lambda` each are placed as shown in figure. The initial phase difference between the sources is zero O. `(d gt gt d)`. Mark the correct statement(s).

Options

A. If `d = (7 lambda)/(2)`, O will be a minima
B. If `d = lambda`, only one maxima can be observed on the screen
C. If `d = 4.8 lambda`, then total 10 minima would be there on the screen
D. If `d = (5 lambda)/(2)`, the intensity at O would be minimum.

Answer

a.,b.,c.,d

Explanation

`Delta x` at `O = d` [path diffenence is maximum at O]
So, if `d = (7 lambda)/(2)`, O will be a minimum. If `d = lambda`, O will be a maxima. If
`d = (5 lambda)/(2)`, O will be minima and hence intensity is minimium.
If `d = 4.8 lambda`, then total minima can be observed on the screen,
5 above O and 5 below O, which correspond to
`Delta x = +- (lambda)/(2) , +- (3 lambda)/(2) , +- (5 lambda)/(2) , +- (7 lambda)/(2) , +- (9 lambda)/(2)`