Final answer:
When two identical spheres with different charges are brought into contact and then separated, the total charge is equally redistributed between them, according to Coulomb's law. This results in each sphere having the same net charge after separation, based on the initial total charge and the nature of the excess charges on either sphere.
Step-by-step explanation:
If two small spheres spaced 20.0 cm apart have equal charge, it suggests that whenever they were brought into contact with each other, they would equally redistribute the total charge between them because they are identical in terms of material, size, and shape. For instance, if sphere A had a charge of −5 nC and sphere B a charge of −3 nC and they are touched together, the total charge of −8 nC would be evenly distributed between the two spheres. After separation, each sphere would have a charge of −4 nC. This principle of charge distribution is based on Coulomb's law that describes the forces between two charges separated by a distance.
Moreover, if one sphere had a certain number of excess electrons and the other an excess charge, bringing them into contact would redistribute these charges so that each sphere ends up with the same net charge. For example, if Sphere 1 had a charge of −9.6 × 10−18 C and Sphere 2 had 30 excess electrons, after contact and separation, both spheres would have the same charge, which we calculate by averaging the sum of both charges. We would also consider electron count or proton count, depending on whether the charges were in electrons or protons, to determine the charge on each sphere following separation.