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)`.

if d = 0.5 mm, `lambda = 5000 A^(@), D = 1m`, at the point 'O' lying on the intersection of screen and the line joining the sources, the order of the fringe formed is

Options

A. 1000 th dark fringe
B. 1000th bright fringe
C. 998th dark fringe
D. 998th bright fringe

Answer

B