Light with wavelength $\lambda$ falls normally on two narrow slits $S_1$ and $S_2$, which are separated by a small distance. On a screen placed far from the slits, bright and dark fringes are seen. The $n$th dark fringe from the central bright fringe is found at point P on the screen. Which equation is valid for every positive value of $n$?
- A$S_2P - S_1P = \frac{n\lambda}{2}$
- B$S_2P - S_1P = n\lambda$
- C$S_2P - S_1P = \left(n - \frac{1}{2}\right)\lambda$
- D$S_2P - S_1P = \left(n + \frac{1}{2}\right)\lambda$