How do you describe the direction of electric current?

Question

I'm having trouble with the whole "Right to left" and "Left to Right" convention. What are these directions relative to? An example problem would be nice.

Answer 1

If you consider the flow of electrons as the current, the flow is from the negative potential to the positive potential.

When an atom looses an electron, the potential becomes positive because a "hole" is formed where the electron should be and the proton is no longer neutralized. I have also seen the current flow described as the "movement" of these holes - and this would be from the positive potential to the negative potential. This conception is important when trying to visualize the concepts involved in some solid state devices.

Other than that, the electron flow (neg to pos) is pretty much the normal consensus.

Answer 2

Way back before Thompson discovered the electron, it was believed that electric current flowed from a positive potential to a negative potential. Using the analogy of water flow in a gravitational field, the idea of water flowing uphill (from a lower potential energy to a higher potential energy) was not observed, so in electricity, the convention was adopted that current flows from positive to negative and this is called the "conventional current". After the electron was discovered to be the primary charge carrier in metals, and since electrons are negatively charged, the "electron current" flows in the opposite direction to the conventioal current.
Now, when electromagnetism came along, it was important to describe the direcion of the magnetic field around a current carrying conductor, so there was one rule for the conventional current (right hand rule) and another rule for the elecron current (left hand rule).

Anyway, that's about it for now. LeAnne is right about the semiconductor theory, where the charge "carriers" are holes, otherwise known as a electron vacancy.