Electrons and electrostatic induction
The electron theory gives a simple explanation of the manner in which opposite charges are induced on the two spherical conductors A and B in Fig. 32.2. Free electrons in the conductors are repelled to the remote side of B by the negative charge on the ebonite rod. When the two conductors are separated the electrons are trapped on B, so that B now has a net negative charge. At the same time A is left with a positive charge, since it has lost the electrons which went on to B.