# Homework Help: Electric field Pre-lab annotation

1. Apr 17, 2017

### Max

1. The problem statement, all variables and given/known data
I am working on annotating the pre-lab for this Electric Field lab and needs to have some help look at my work. The second question of the Pre-Lab is comparing the answers between two persons Kate and Victor. Based ib this diagram below

* o (-1) *
* o (+1) *
* o (-1) *
(the separations between the three locations * to the three charges equal.

Victor said:" The net electric force at point R is to the left. The vertical components of the field due to two negative charges cancel out, and the positive charge ism closer to point R than the negative charges are,

Kate:" I agree the net electric charge field is along the horizontal axis. But there are two negative charges, and only one positive charge. this means the net electric field points to the right"

2. Relevant equations
Use vector algorithms

3. The attempt at a solution:
I said: "
Victor said:" The net electric force at point R is to the left. The vertical components of the field due to two negative charges cancel out, and the positive charge is closer to point R than the negative charges are,

Kate:" I agree the net electric charge field is along the horizontal axis. But there are two negative charges, and only one positive charge. this means the net electric field points to the right"

The red ones are not correct because the x-component of the electric field vector due to the positive will make the vector sum of two negative vectors shorter, but not sufficient to shift the direction of the vector sum due to the negative charges. -> Kate was more problematic due to the red-bolded reasoning.

Do you agree with me that Victor is totally right or something else that I didn't notice?

2. Apr 17, 2017

### kuruman

It would help if we knew where point R is. Can you post a reasonably drawn diagram? A photo of one should suffice if it is clear.

3. Apr 17, 2017

### Max

R is a random point. I think I would say it's in a straight line
* o (-1) *
R* o (+1) *
* o (-1) *

R is that point!

4. Apr 17, 2017

### kuruman

So you have three charges equally spaced on a line. How does the distance x between point R and the line of charges compare with the distance y between charges?