BITSAT 2017 Paper

A disk of radius a/4 having a uniformly distributed charge 6 C is placed in the x−y plane with its centre at (–a/2,0,0). A rod of length a carrying a uniformly distributed charge 8 C is placed on the x-axis from x=a/4 to x=5a/4. Two point charges –7C and 3C are placed at (a/4,–a/4,0) and (–3a/4,3a/4,0), respectively. Consider a cubical surface formed by six surfaces x=±a/2,y=±a/2,z=±a/2. The electric flux through this cubical surface is