Conventional Current vs Electron Flow in Electrical Circuits

Summary

In this video, the presenter explains the difference between conventional current and electron flow, two competing theories of how electricity moves. It begins with Benjamin Franklin and the glass tube experiments that led him to label one end positive and the other negative, suggesting electricity flows from positive to negative. The narrative then covers Joseph John Thomson, who discovered electrons and showed that they move from negative to positive, opposite to Franklin's assumption. The video emphasizes that while electrons actually flow the other way, most electrical engineering formulas and circuit diagrams default to conventional current because the results remain unchanged. It also notes that changing the nomenclature on batteries is impractical, so conventional current persists in textbooks and schematics. The takeaway is to default to conventional current when discussing circuits, while acknowledging the true electron flow studied by scientists.

Introduction

This video from Engineering Mindset explores a fundamental concept in electricity that often causes confusion: conventional current versus electron flow. The discussion maps out the historical development from early experimentation to modern circuit analysis, explaining why the field uses a sign convention that does not depend on which particles actually move.

Historical background

The narrative begins with Benjamin Franklin's experiments in static electricity. When a glass tube was rubbed with a cloth, observers noticed an invisible charge that could shock someone else who touched the tube. Franklin interpreted this as an accumulation of a fluid inside the material, declaring one end of the tube positive and the other negative. This led to the conventional current convention, adopted by battery manufacturers and maintained to this day. The analogy to water flowing from high to low levels helps justify the idea that current moves from positive to negative, reinforcing the naming.

Discovery of electron flow

As experimentation advanced, Joseph John Thomson demonstrated that the charge carriers inside wires are particles, which he named electrons. He showed that electrons flow in the opposite direction to the conventional current, moving from negative to positive. The video notes that Franklin did not realize rubbing the silk cloth removed electrons, which means electrons actually flow from the person toward the glass tube in his setup.

Why conventional current endures

Despite the actual direction of electron flow, the standard engineering and physics formulas used to design circuits do not rely on the specific movement of charge carriers. The mathematical results remain the same regardless of whether you measure current as positive charges moving from positive to negative or electrons moving from negative to positive. It is simply a convention that simplifies analysis and communication. Because changing the terminal labels on billions of batteries is impractical, conventional current remains the default in circuit drawings and teaching materials. Some textbooks show both viewpoints, but the convention persists in education and industry.

Practical implications

The video emphasizes that when designers speak about electricity, they default to conventional current. Scientists and engineers know the electrons flow the other way, but this distinction does not alter the outcomes of most circuit calculations, and it is mainly a matter of sign convention. Understanding both perspectives helps students avoid confusion, but for everyday circuit work, conventional current is the standard reference point.

Conclusion

The key takeaway is to recognize the historical roots of conventional current, understand the actual electron flow, and use conventional current as the default framework when analyzing, drawing, or teaching circuits. The video invites viewers to continue exploring electricity and electrical engineering with more lessons and related content on the site.