Now if , at all the points on far away screen, the waves originating from different parts of the slit will be partially in phase, and we observe finite intensity of wave there. This automatically explains the bending of waves at sharp obstacles.

For , the secondary wavelets originating from the slit, when reach the screen, will have different phases. At points, where path difference is zero (point on the screen for which the line joining center of slit to screen is perpendicular to the plane of slit), the intensity will be maximum and will slowly diminish as we move further away from this point. At point where path difference become the minima will be observed and as we move further again the intensity will increase.