Under what conditions can the electric flux φE be found through a closed surface?

Question

Under what conditions can the electric flux φE be found through a closed surface? (A) If the magnitude of the electric field is known everywhere on the surface. (B) If the total charge inside the surface is specified. (C) If the total charge outside the surface is specified. (D) Only if the location of each point charge inside the surface is specified.

Tardigrade Admin · Accepted Answer

We should know the total charge inside. There is no contribution in the flux due to outside charges. Also, we should know both magnitude and direction of electric field at any point on the surface.

Q. Under what conditions can the electric flux ϕE​ be found through a closed surface?

If the magnitude of the electric field is known everywhere on the surface.

If the total charge inside the surface is specified.

If the total charge outside the surface is specified.

Only if the location of each point charge inside the surface is specified.

We should know the total charge inside. There is no contribution in the flux due to outside charges. Also, we should know both magnitude and direction of electric field at any point on the surface.

Q. Under what conditions can the electric flux $ϕ_{E}$ be found through a closed surface?