a. In the process of induction, metal objects are positive because electrons are pushed out of the object to the earth. The mass of the object decreases by an amount equal to the mass of the electrons leaving the metal object.
b. During the induction process, electrons are drawn from the earth to the object, so that the metal object becomes negative. The mass of the object increases by an amount equal to the mass of "excess" electrons dragged onto the object.
