# Homework Help: 3 point charges on the vertices of an equilateral triangle

1. Nov 5, 2009

### Unemployed

1. The problem statement, all variables and given/known data

3 equal point charges on the vertices of a triangle. If the each of the charges are doubled, why is the resulting force on each charge quadrupled?

2. Relevant equations

F= Fx +Fy

F= kqk2/r^2

3. The attempt at a solution
I got doubled

2. Nov 5, 2009

### housemartin

well the force acting on charged particle (Coulomb's law) is equal to:
$$F=k\frac{q_1 q_2}{r^2}$$
if distance is left same, and charges is doubled, you get:
$$F=k\frac{2q_1 2q_2}{r^2}=4k\frac{q_1 q_2}{r^2}$$
so the force is bigger four times