|MadSci Network: Physics|
Dear Alan, You are right, there is some confusion about the direction an electric current is flowing. When electricity was discovered, nobody knew how it works and electrons were unknown. So the scientists just defined one of the poles as "positive" and said that the current is flowing from positive to negative. That still is the definition of an electrical current's flow direction. However, later scientists discovered that in most (but not all) materials current is carried by negatively charged electrons, which travel from negative to positive. The electron flow is thus opposite to the current flow. In some materials (e.g. electrolytic solutions) the current is carried by positive ions, which travel in the current's direc- tion. And in semiconductors there can be currents of negative or positive carriers, depending on the doping. Greetings from Singapore, Frank Berauer
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