In 1747, Benjamin Franklin ran experiments with silk, wool, glass rods, and copper rods that led him to the law of conservation of charge, showing that like charges repel and opposite charges attract. Franklin arbitrarily assigned the labels positive and negative to the two types of charge, a convention that turned out to mean the particles later identified as electrons carry the negative charge. Franklin is also credited with the kite experiment demonstrating that lightning is electricity, which led to his invention of the lightning rod.
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Franklin's arbitrary naming convention means electron flow runs opposite to the direction electrical engineers define as conventional current, a mismatch later engineers still have to work around.
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1:30Today we are going to start in 1747 with the discovery of the conservation of charge. Yeah, this is the only one that happened before our country's independence. 1747 Benjamin Franklin discovers the fundamental law of the conservation of charge. He was doing a bunch of experiments with silk and wool and glass rods and copper rods. This is something that actually I remember seeing in my undergrad days as well where you know you you bring those two together and they repel each other but then the other one you bring in and they attract and the like likes repel opposites attract. That was him. Um he made the electron the negative charge
2:12unknowingly. He didn't know about electrons, right? But he just said, "Okay, whatever this glass thing is doing, that's going to be negative." And it turns out that's what the electrons were because those are the carriers. And I think a lot of electrical engineers would be um if they had a time machine, they would go back and be like just just do the opposite thing because then electrons would be positive and I don't have to worry about oh the current is this way but the flow of electrons is this way and so on and so forth. He also did the the kite experiment to show that lightning is electricity and he invented the lightning rod. So great founding father also a great scientist.