Two monochromatic coherent point sources $S_1$ and $S_2$ are separated by a distance L. Each source emits light of wavelength $\lambda$ where $L>>\lambda$ The line $S_1{S}_2$ when extended meets a screen perpendicular to it at point A. Which of the following is correct

Locus of points on screen for which $S_{1}P-S_{2}P=$ constant will be circular in nature.

Maximum will be formed if $S_{1}A-S_{2}A=n\lambda$, where n is an integer. 

There will be a variation of intensity on the screen, as the path difference is varying for the points on the screen.