# Voltage between two points with linear electric filed integral

1. Nov 20, 2014

### baby_1

1. The problem statement, all variables and given/known data
Hello
Assume that I want to find voltage between two points that place in different location (for example A at r1 and B at R2) now I'm confusing
1-when we use positive and negative linear electric filed integral

or

2-and how can we define integral limitation?

Thanks

2. Nov 20, 2014

### Staff: Mentor

Why don't you make a simple example and test your ideas in order to find out? The electric field between the plates of a parallel plate capacitor is uniform and simple to calculate when a potential difference is placed on them. Set up the integrals and see what matches the reality.

Doing the above would have made an excellent entry for your "Attempt at a solution" section of the template...

3. Nov 20, 2014

### baby_1

Thank you gneill
yes I did it before for two plate that we know the voltage across from plates.but in space that we didn't know the exact voltage value between two point what should we do? as I see different book some of them use negative but others use positive integral form

4. Nov 20, 2014

### Staff: Mentor

The choice will depend upon your choice of coordinate axes and the direction of the dl's compared to them. The dot product E.dl takes care of the field's direction with respect to the dl's, but you need to evaluate whether your dl's themselves will be positive or negative depending upon the coordinate system.