The direction of current comes from the fluid theory of electricity first developed around 1600 AD. By 1700 AD the fluid was divided into special fluids, "vitreous" associated with electricity on glass-like substances, and "resinous" associated with electricity on amber, wax and rubber. Then in 1747, Ben Franklin arbitrarily
assigned + and -. + to vitreous and - to resinous.
The "flow" of current was thought to go from + to -.
It wasn't until the idea of the atom at the beginning of the 20th century that the notion of "fluid" was replaced. Then electrons were thought of as marbles moving from - to +. This satisfied a lot of minds, until quantum physics of the post-Einstein world settled in. Electrons are now understood as packets of vibration with indistict edges (edges that blur off into infinity) that also have mass and motion.
In a conductor, such as copper, electrons move into the open places in the outer electron shell of the copper atoms. The electrons tend to stay in a small group of atoms, bouncing back and about, while the place that the electrons move into, the holes
in the electron shell, actually is what flows as current
. So, the holes move from + to -
and we are back to Ben Franklin's arbitrary definition again.
You might say, current is the movement of nothing from + to -.
There are more understandings coming.
What matters for us as electricians, IMHO, is that we understand the macro
electromagnetic and electromechanical effects. Few of us have to get a logic state change to occur based on micro
current flow through a few Angstroms of semiconductor material, with all its quantum realities.
The pre-Einstein model of negative charged electrons moving like marbles down a gutter works well for most people. When this model is connected with magnetic flux moving from North to South, all that is necessary is to consistantly apply the Left Hand Rules
But, . . . just to balance this,
. . .if you want to use Ben Franklin's definition or the quantum physics definition of current, i.e., current flows from + to -, AND magnetic flux moves (this is the same as above) from North to South, all that is necessary is to consistantly apply the Right Hand Rules
The two "rule" links are to animated Quicktime gifs that take a bit to load, but illustrate the point.
[This message has been edited by ElectricAL (edited 07-02-2002).]