Conventional Current vs. Electron Flow Defined
Conventional electric current is defined as the theoretical direction in which positive charges would flow within an electrical circuit. This means it flows from a point of higher electric potential (the positive terminal) to a point of lower electric potential (the negative terminal). This convention was established before the discovery of electrons and their negative charge.
The Historical Basis of the Convention
In the 18th century, Benjamin Franklin, among others, assumed that electricity flowed from positive to negative. Although we now know that in most metallic conductors, negatively charged electrons are the actual charge carriers and move in the opposite direction (from negative to positive), the 'conventional current' definition remains widely used in electrical engineering, physics, and circuit diagrams due to its established framework and consistent application.
Practical Example in a Simple Circuit
Consider a simple circuit powered by a battery. According to the conventional current definition, the current flows out of the battery's positive terminal, through the circuit's components (like a light bulb), and returns to the negative terminal. However, the electrons are physically moving from the negative terminal, through the components, and towards the positive terminal, attracted by the higher potential.
Importance in Modern Electrical Theory
Despite the discrepancy with actual electron flow, adhering to conventional current is crucial for correctly applying fundamental electrical laws such as Ohm's Law and Kirchhoff's Laws. It provides a consistent, logical framework for analyzing and designing electrical circuits, allowing engineers and scientists worldwide to use a common language and understanding when discussing electrical phenomena, regardless of the microscopic charge carrier movement.