Question

Careful measurement of the electric field at the surface of a black box indicates that the net outward flux through the surface of the box is `8.0 xx10^(3) Nm^(2)`/C. If the net outward flux through the surface of the box were zero, could you conclude that there were no charges inside the box? Why or Why not?

Answer 1

Net outward flux `=0`
Then, we can conclude that the net charge inside the box is zero. i.e., the box may have either zero charge or have equal amount of positive and negative charges. It means we cannot conclude that there is no charge inside the box.