Direction of Line of Electric Force

Theorem
Let $\mathbf E$ be an electric field.

Let $L$ be a line of force within $\mathbf E$.

Then $L$ has one of the following properties:


 * $(1): \quad$ Begins on a positively charged body and ends on a negatively charged body


 * $(2): \quad$ Begins on a positively charged body and goes to infinity without terminating


 * $(3): \quad$ Comes from infinity without a start point and ends on a negatively charged body.