Question

A charge Q is placed at a distance a/2 above the centre of a horizontal, square surface of edge a as shown in the following figure . Find the flux of the electric field through the square surface.

Answer 1

Given:-
Edge length of the square surface = a
Distance of the charge Q from the square surface = a/2
Area of the plane = a²
Assume that the given surface is one of the faces of the imaginary cube.
Then, the charge is found to be at the centre of the cube.
A charge is placed at a distance of about `"a"/2` from the centre of the surface.
The electric field due to this charge is passing through the six surfaces of the cube.
Hence flux through each surface,

`phi = "Q"/∈_0 xx 1/6 = "Q"/(6∈_0)`

Thus, the flux through the given surface is `"Q"/(6∈_0).`