In the arrangement shown, a screen is placed normal to the line joining the two point coherent sources `S_(1)` and `S_(2)`. The interference pattern consist of concentric circles. `lambda` is the wavelength of light `(D gt gt d)`.

The phase difference of the interfering light at point P is

Options

A. `(2pi)/(lambda) d cos theta`
B. `(2pi)/(lambda) d. cos^(3) theta`
C. `(2pi)/(lambda) d cos^(2) theta`
D. `(2pi)/(lambda)(d)`

Answer

A