Electrostatics

In a cuboid of dimension \(2 \mathrm{~L} \times 2 \mathrm{~L} \times \mathrm{L}\), a charge \(q\) is placed at the center of the surface '\(\mathrm{S}\)' having area of \(4 \mathrm{~L}^{2}\). The flux through the opposite surface to '\(\mathrm{S}\)' is given by