A student uses two metal spheres of unequal size in an experiment. Both spheres are placed on insulating stands. The small sphere has a net charge of +70 nC. The large sphere is uncharged.
As the two spheres are brought close the student sees a spark between the spheres. It is determined that the final charge on the small sphere is +30 nC.
What is the final charge on the large sphere; and what direction did electrons move when the spark occurred?