A cube of edge a is kept on x-axis in a region where electric field varies with distance as `E = kx hati`. Total electric flux associated with the cube is-

Options

A. `ka^(3)`
B. `-3ka^(3)`
C. `4ka^(3)`
D. zero

Answer

A

Explanation

`phi_(ABCDA) = (4ka) hati a^(2)hati`
`phi_(ABCDA) = 4ka^(3)`
`phi_(EFGE) = (3ka)hati a^(2)hati =- 3ka^(3)`
`phi_("cube") = 4ka^(3)-3ka^(3)`
`phi_("cube") = ka^(3)`