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Dr. Christopher S. Baird

Why were electrons chosen to be negatively charged? Wouldn't it make more sense to call electrons positively charged because when they move they make electricity?

Category: Physics      Published: December 18, 2012

neon sign
Electric currents in a gas discharge sign are carried by both electrons and ions. Relabeling the electrons as positive would require relabeling the moving ions as negative and nothing would be gained. Public Domain Image, source: NIH.

First of all, "electricity" does not mean "moving electric charge". If "electricity" meant "moving electric charge" then "static electricity" would mean "stationary moving electric charge," which is nonsense. "Electricity" is a general term describing all effects connected to electric charges. When people use the word "electricity" to describe what is going on in an electric wire, they usually mean "electric current".

Secondly, electric current is not just a bunch of moving electric charges. Electric current is the net movement of electric charges and the movement of electric field disturbances connected to the charges. That is why electrical signals in a wire, such as telephone calls, travel on the order of the speed of light while the electrons themselves travel much slower. If electric currents were nothing more than moving electrons, then it would take 6 months for your voice on the telephone call to reach the other side of town. The objects in a material that are contributing the most to an electric current are called the charge carriers.

Third, electric charge carriers aren't always electrons and they aren't always negative. In fact, in the natural world, the charge carriers are usually not just electrons. In animals, the electric charge carriers are primarily sodium, potassium, calcium, and magnesium ions, all positively charged. They are the things that are moving when a nerve passes an electric signal. In the ionosphere, the charge carriers are oxygen, hydrogen, and helium ions along with electrons. In a gas discharge sign, the electrical current is due to ions and electrons. In lightning, it's both ionized air molecules and electrons that are moving. The solar wind is in fact a blast of electrical current from the sun comprised of protons and electrons. In semiconductors, like those used in computer chips, the charge carriers are holes and electrons. In the ocean, it's the movement of salt ions, and not electrons, that sustains an electrical current. In metals, like in household electrical wire, the charge carriers are indeed just electrons. Renaming electrons as positively charged would require renaming almost all the other charge carriers as negatively charged. Such an action would probably make things less simple, not more. Benjamin Franklin was the one who first chose to call electrons negative and protons positive. According to the textbook "Physics for Scientists and Engineers" by Raymond A. Serway, Franklin identified electric charge carriers after a series of rubbing experiments. Without much knowledge of the underlying physics, he simply made a choice that made sense to him by calling electrons negative.

Topics: charge convention, electric charge, electrical current, electricity, electromagnetism, electron, electrons