Electric Flux Through a Cube

A corner is shared by 8 identical cubes (a 2×2×2 block). The charge can't tell them apart, so each cube — including yours — gets 1/8 of the total q/ε₀.

q/2ε₀. The charge sits on the surface, so only half its field lines enter the cube; the other half escape into the opposite half-space.

No. As long as the charge is fully enclosed, the total flux is always q/ε₀ regardless of where inside it sits — that's the heart of Gauss's law. It only drops when the charge moves onto the surface (face/edge/corner).

The 3 faces touching the corner get 0; the 3 far faces share the q/8ε₀ equally → q/24ε₀ per far face. (A common JEE-level follow-up.)

The field lines from a charge lying on that face are in the plane of the face — they graze it instead of piercing it, so the perpendicular flux through it is zero.