AIIMS 2018 Physics Interference of Light MCQ Question

When two coherent sources of light interfere constructively at the central maximum, the intensity is given by $I_0 = (2A)^2 = 4A^2$. In contrast, if the sources are incoherent, they do not produce interference; thus, the intensity at the same point is simply the sum of the individual intensities, which is $I = A^2 + A^2 = 2A^2$. Therefore, the intensity at the central maximum for incoherent sources is $I = 2I_0/4 = I_0/2$, making option D correct. Other options are incorrect as they either overestimate the intensity due to interference effects or miscalculate the contributions from incoherent sources.