Three identical point charges of 2.0 mC are placed on the x-axis. The first charge is at the origin, the second to the right at x = 50 cm, and the third is at the 100 cm mark. What are the magnitude and direction of the electrostatic force which acts on the charge at the origin?

The law of conservation of electric charge: The net amount of electric charge produced in any process is zero. or
No net electric charge can be created or destroyed.

Three properties of conductors in static equilibrium.
1. The electric field inside a conductor is zero in the static situation.
2. Any net charge on a conductor distributes itself on the surface.
3. The electric field is always perpendicular to the surface outside of a conductor.

Gauss's law: The total flux summed over any closed surface is equal to the net charge enclosed by the surface divided by eo.