Homework Help: Force of a Dipole

1. Oct 16, 2013

elli

1. The problem statement, all variables and given/known data
A dipole is centered at the origin, and is composed of charged particles with charge +e and -e, separated by a distance 7 ✕ 10-10 m along the y axis. The +e charge is on the -y axis, and the -e charge is on the +y axis. A proton is located at <0, 3 ✕ 10-8, 0> m. What is the force on the proton, due to the dipole?

2. Relevant equations
E=k*[(2*q*s)/(r^3)]
F=E*q

3. The attempt at a solution
I calculated the electric field using the equation for a charged particle on axis with a dipole. I then multiplied that electric field by the charge of the proton(1.6e-19)
I'm very lost with all this dipole stuff. Any and all help is appreciated!

2. Oct 16, 2013

Staff: Mentor

Show the equation that you used. Sketch the relative positions of the particles. Hint: you'll only need one axis to do it!

3. Oct 16, 2013

elli

What I have is k=9e9
q=-1.6e-19
s=7e-10
r=(3e-8)-(7e-10/2)=2.965e-8
E=-77342.2N/C
The charge of the proton is 1.6e-19
I think the force should therefore be (0,1.6e-19*-77342.2,0)=(0,-1.237e-14,0).
But that's just not working:(

4. Oct 16, 2013

Staff: Mentor

What coordinate axis are the dipole electrons on?

What coordinate axis is the proton on?