This is about Vidoe 17 in Wave optics IIT JEE package. about shape of fringesin YDSE. When two point sources are on Y axis and screen is in XY plane the screen will be parallel to light beams and no light will fall on screen, then how interference is possible? Same doubt in case (iii) where screen is in XZ plane and fringes are shown as concentric circles? Pl. clarify.