Re: How did Franklin take the idea of electricity and make it useable?

Hi, John!

I'm afraid this question is an example of something "we all know" that just ain't so!

The ancient Greeks knew that if you rubbed amber -- fossilized tree sap -- with a cloth, the amber would attract lightweight objects, like small pieces of paper. Their word for amber was elektron, from which we get the modern words "electron", "electricity", and so forth.

"Electricity" refers to the flow of electrical charge. Usually when we say this we mean the flow of electrons in a conductor such as copper wire. "Static" electricity means an excess or dearth of charge that's "waiting" to flow, such as in the amber, or when the earth and clouds are "charged" just before a lightning strike. (In lightning, the charge becomes high enough to ionize the air, making it conductive. The bright flash is the ionized air; the thunder is the explosion of the air rapidly expanding outward. It's the same thing as a static "shock", just much much larger. Franklin actually just got a bit of static charge in his glass jar -- he would probably have died if actually struck.)

The very first electrical battery was created in the year 1800 by the Italian scientist Alessandro Volta. He placed together alternating disks of silver and zinc metal, separated by paper soaked in salt water. A chemical reaction among the silver, zinc, and salt water caused electrons to migrate from the silver to the zinc, making the zinc negatively charged (from excess electrons) and the silver positively charged (from not having enough). When he connected one end of the battery to the other, an electric current flowed.

Nearly all batteries work in much the same way: two unlike electrodes -- usually metal or carbon -- make a "sandwich" with a wet or moist conducting material (an electrolyte) between them. Opposite electrical charges build up on the electrodes. Using wires, we connect the battery to something that allows the charge to flow while using the flow ("current") to perform some kind of work. We may use it for lighting a flashlight, powering a radio, or starting a car.

(Strictly speaking, we should call a single pair of electrodes separated by an electrolyte a cell -- a battery is really two or more cells connected together.)

The other way we generate electricity -- most of it, in fact -- is by running an electric generator, also known as a dynamo. A generator is just like a permanent-magnet electric motor. Rather than using electric current to cause the motor to turn, we force the motor to turn, producing electric current. We use other sources of energy -- falling water, steam from water boiled by burning coal/oil/gas, steam from water boiled by the heat of nuclear reactions, the explosive burning of a mixture of air and gasoline -- to drive the generator.

The principle of the generator, known as electromagnetic induction, was first demonstrated in 1831 by the English scientist Michael Faraday. He showed that an electric current will flow when a wire is moved through a magnetic field. He then used this knowledge to build the first dynamo.

Hope this helps!

Best wishes,

Aaron Endelman