Understand Field Lines: Positive & Negative Atoms

[Drizzy]

Homework Statement

https://www.google.se/search?q=fält...h&q=physics+field+lines&imgrc=rKecBAfLOMsOoM:

Why are the field lines on the positive atom pointed out but the negativ is inward?

Homework Equations

The Attempt at a Solution

 

[Ray Vickson]

Homework Statement

https://www.google.se/search?q=fältlinje&rlz=1C1_____enSE665SE665&espv=2&biw=1366&bih=643&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMI9dTNgquLyQIVhJIsCh1NxQZU#tbm=isch&q=physics+field+lines&imgrc=rKecBAfLOMsOoM:

Why are the field lines on the positive atom pointed out but the negativ is inward?

Homework Equations

The Attempt at a Solution

Because they point in the direction of the force on a POSITIVE charge.

 

[gneill]

It's the agreed upon convention. After all, "positive" and "negative" are just names we have attached to the two charge types. It could've gone either way. Having decided to make one "positive" and the other "negative", the field line directions follow in order to make them agree with the resulting vector math.