Q 1.17 (b): 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 .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?
Using Gauss's law , we know that
Since flux is zero, q = 0, but this q is the net charge enclosed by the surface.
Hence, we can conclusively say that net charge is zero, but we cannot conclude that there are no charges inside the box.