# Torque of electrical dipole moment

1. Sep 28, 2010

### gambit24

1. The problem statement, all variables and given/known data
Calculate each torque of a dipole rotating at 30 degree increments for 180 degrees.

Dipole: s=.55 cm q=+/- 3.7nC
Distance from point charge to axis of dipole = 14.3 cm
point charge = +4.5 nC

So there should be 8 phases and 7 torques (number 4 doesn't have a torque because the dipole is collinear with the point charge. Pre

2. Relevant equations

T = radial length x point force on axis perpendicular to dipole
F = k (q1q2) / r2
E = k q/r2 x r
c2 = a2 + b2 - 2abcosC

3. The attempt at a solution

I've drawn all the diagrams and found out the different locations of each, but I don't know how to find the force on the point on the axis. I've treated the charges like three different points on an observation point but can only determine an electric field. Now, I dont need help on all of this, but if you know the electric field, which q do you use to find the force vecotr, and what are the new units of torque? I looked it up, and it said N*m*s, but the equation I have (given by my teacher) only multiplies N and m.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution