# Electrical field of an equialateral triangle

1. Oct 24, 2009

### phy43

1. The problem statement, all variables and given/known data
An equilateral triangle is formed with 3 rods, each with a length of 10cm. Two of them carry a charge of +63nC and 1 carries a charge of -63nC. The charge is uniformly distributed along each rod. What is the magnitude of the electric field at the center of the triangle?

2. Relevant equations
E_Rod = KQ / (d*sqrt(d^2 * (L/2)^2))

3. The attempt at a solution
Center of triangle is 4.33cm, or .0433m from each rod.

Constant K = 9.0*10^9
Q: Charge
d: Distance
L: Length of rod
E_Rod = KQ / (d*sqrt(d^2 * (L/2)^2))
E_Rod = (9.0*10^9)Q / (.0433sqrt(.0433^2 + .05^2))
Plugging in 63*10^9, 63*10^9, and -63*10^9, I receive:
E_Rod(1,2,3) = 197976,197976,-197976

Adding the three gives me a net E_rod = 197976, which is wrong.

2. Oct 24, 2009

### willem2

draw a picture of the forces involved. Split them up in horizontal and vertical components and add those.

3. Oct 24, 2009

### tiger1

Thanks.. Figured it out. Also figured out I was calculating the triangle height wrong.