A point charge q is placed at the centre of a cube. What is the flux linked.
a with all the faces of the cube?
b. with each face of the cube?
c. if charge is not at the centre, then what will be the answer of parts a and b ?

Options

A. `(q _(0))/( epsi _(0))`
B. `0`
C. `(q _(0))/( 3 epsi _(0))`
D. `(q _(0))/(6 epsi _(0))`

Answer

C

Explanation

`(q _(0))/( 3 epsi _(0))`
Flux through the entire cube using Gauss.s law `phi = (q _(0))/( epsi _(0))`
Flux through one surface `= (1)/(6) (( q )/(epsi _(0))) = ( q _(0))/( 6 epsi _(0))`
Flux through two surface `=2 ((q _(0))/( 6 epsi _(0)) ) =( q _(0))/( 3 epsi _(0))`