Two electrons with a charge of magnitude 1.6×10-19 C in an atom are separated by 1.5×10-10 m, the typical size of an atom. What is the electric force between them?

, repulsive

Explanation:

The magnitude of the electric force between two charged particles is given by Coulomb's law:

where:

is the Coulomb's constant

are the two charges of the two particles

r is the separation between the two charges

The force is:

- repulsive if the two charges have  same  sign

- Attractive if the two charges have opposite signs

In this problem, we have two electrons, so:

is the magnitude of the two electrons

is their separation

Substituting into the formula, we find the electric force between them:

And the force is repulsive, since the two electrons have same sign charge.