Electric Field Conseptual Question

[JayDub]

Hey There, I am studying for my exam here coming up in two weeks and I came across a question with electric field. Now I can figure it out (E = kq/ r^2) but I was wonder which direction does it travel in? For example if the question was something like: A uranium nucleus contains x protons, what is the direction of the electric field from this nucleus? Either away from the nucleus or towards it. I know that is is away from the nucleus, but why is that? Thank you.

Josh

 

[teken894]

Definition

1. A vector field, usually denoted by E, defined as follows: at a given time and at each point in space the force experienced by a positive charge (sometimes called a test charge) at that point divided by the magnitude of the charge, taken to be sufficiently small that it does not affect the positions and velocities of all other charges. The set of all vectors thus obtained is the electric field, although this term is often used for its value at any given point. ... (http://amsglossary.allenpress.com/glossary/browse?s=e&p=15")

It's simple, the electric field is in the direction of force experienced by a small positive test charge. Hence, if protons repel positive charges (force away from the nucleus), so it points away. Convention and definition is the reason.