Two identical narrow slits `S_(1)` and `S_(2)` are illuminated by light of wavelength `lambda` from a point source P. If, as shown in the diagram above the light is then allowed to fall on a scree, and if n is a positive integer, the condition for destructive interference at Q is that

Options

A. `(l_(1)-l_(2))=(2n+1)lambda//2`
B. `(l_(3)-l_(4))=(2n+1)lambda//2`
C. `(l_(1)+l_(2))-(l_(3)+l_(4))=nlambda`
D. `(l_(1)+l_(3))-(l_(2)+l_(4))=(2n+1)lambda//2`

Answer

D