A point charge q is kept at a corner of a cube

Options

A. Electric flux linked with individual faces of the cube may be zero
B. Electric flux linked with individual faces of the cube may be non-zero
C. Electric flux linked with a certain face of the cube may be `q//8epsilon_0`
D. Electric flux linked with a certain face of the cube may be `q//24epsilon_0`

Answer

A, B, D

Explanation

Point charge is kept at the corner of the cube. Hence, the three faces, which contain this corner, will bear no electric flux because electric field intensity for these faces will be parallel to that face only. So, option (a) is corsect. Electric flux is linked with the remaining three faces of the cube and from symmetry it is equal for these three faces. Thus, option (b) is also correct.
We can think of eight cubes sharing one corner where the charge is located. The point charge gets completely enclosed within this bigger cube and total flux becomes `q//epsilon_0`, which is equally divided among all eight cubes. Hence, `q//8epsilon`, will be the electric flux share for one of the eight assumed cubes.
In each cube this electric flux is equally divided between three faces only. Hence for a single face, it is `q//24epsilon_0` Therefore, option (c) is incorrect but (d) is correct.