Are electric sources and sinks symmetrical?

Question

When discussing sources and sinks for the property of divergence of electric fields, why is the positive polarity uniquely selected as a source and the other a sink? Aren't they both sources and sinks of opposite polarity? The negative is a source of negative field and a sink for positive field and the positive a source for positive field and a sink for negative field. This conditions students (me) to think in a confused way.

Please don't address nomenclature. The question of charge naming convention has an answer here: Why is the charge naming convention wrong?. This question is about the physical properties of the fields.

Answer 1

What I mean is that there seems to be two different fields because they produce opposite deflections on moving test charges. There is no way to convert the field of an electron into the field of a proton & vice versa. It seems that they must be intrinsically different

If there is an intrinsic difference, then it must be detectable in principle.

Suppose that there is an electric field in some region of space containing no charge and that, in this region, the electric field is uniform in magnitude and parallel to the $z$ axis:

$$\mathbf{E} = E_0\mathbf{\hat{z}}$$

Can you think of a way, using only a test charge in this region of space, to determine if this field is due to positive or negative charge, i.e., to detect this intrinsic difference you believe exists?

Answer 2

There is no "positive field" and "negative field", there is only the electric field (and the magnetic one, but that's another discussion). The reason the positive charge centers are considered sources and not sinks is because of an arbitrary convention, the math would work out just as well if it were the other way around, although there might be a few more sign problems if the "negative source" convention were used.

Answer 3

(XKCD #567)

As far as the electric fields themselves are concerned, which side is positive (source) and which side is negative (sink) is just a convention. However, when it comes to the flow of electricity, our convention is backwards. In the majority of cases, the charge carrier is an electron which starts from the negative side (sourced from the sink) which travels "backwards" through the circuit to the positive side (sinked into the source)! All because Benjamin Franklin had to pick a side to be positive, and he picked the less convenient one.

In semiconductors sources and sinks become more important. Each region of semiconductor is doped to be either P-type or N-type. This creates either a glut of holes (atoms which are short 1 electron) or a glut of mobile electrons. In these situations, the direction becomes important because one charge carrier can be replenished faster than the other. Of course even here, the difference is contextual. PNP transistors use the exact opposite charge carrier of NPN transistors.