A negative charge of 20 x 10-6C and another charge of 15 x 10-6C are separated by as distance of 0.7 m. What is the magnitude of the electrical force between the two charges:
answer to the closest 0.1 N

Approximately , assuming that the volume of these two charged objects is negligible.

Explanation:

Assume that the dimensions of these two charged objects is much smaller than the distance between them. Hence, Coulomb's Law would give a good estimate of the electrostatic force between these two objects regardless of their exact shapes.

Let and denote the magnitude of two point charges (where the volume of both charged object is negligible.) In this question,  and .

Let denote the distance between these two point charges. In this question, .

Let denote the Coulomb constant. In standard units, .

By Coulomb's Law, the magnitude of electrostatic force (electric force) between these two point charges would be:

.

Substitute in the values and evaluate:

.

a and c

c is 100% but i am confused in a