7. III Two identical metal spheres A and B are in contact. Both are initially neutral. 5.0times 10^11 electrons are added to sphere A, then the two spheres are separated Afterward, what are thelcharge of A and the charge of B?

When two identical metal spheres A and B are in contact, they share the charge equally. Initially, both spheres are neutral, meaning they have no charge.<br /><br />When $5.0\times 10^{11}$ electrons are added to sphere A, it gains a negative charge. Since the spheres are identical, the charge will be shared equally when they are in contact. Therefore, each sphere will have half of the total charge, which is $-2.5\times 10^{11}$ electrons.<br /><br />After the spheres are separated, sphere A retains its charge of $-2.5\times 10^{11}$ electrons, and sphere B also retains its charge of $-2.5\times 10^{11}$ electrons.<br /><br />So, the charge of sphere A is $-2.5\times 10^{11}$ electrons, and the charge of sphere B is $-2.5\times 10^{11}$ electrons.