Feb 12, 2012

How Electrons Were Found (It took 2 millenniums)

Some hard-to-understand principles of physics feel easier to understand once you know the history of how it was discovered. Electrons are a good example-it actually took 2 millennia to go from faint recognition of it to a complete understanding.
It started in ancient Greece- By 600 BC, it was already "discovered" that amber (you know, the rock that has bugs trapped inside it, like in Jurassic Park?), when rubbed with cloth, attracted bits of pieces of feather and dust.

But they didn't know how- so it earned the title "magic rock".

In the 16th century, William Gilbert of Britain found out that the mysterious force could be transferred to other objects. When you placed scrubbed amber close to an unscrubbed one, the latter amber acquires the former's properties, which is to attract bits of dust and stuff.

By the 18th century,scientists began to realize there were 2 types of these forces-one that attracted each other and another that repulsed.Then, in the 1750s, Benjamin Franklin guessed that these were caused by little bits of electricity that carried positive charge moving across objects.
He thought that when there were too much of it the object carried positive charge and when there wasn't
enough of it it was negatively charged. He also thought that the "bits of electricity" (or negatively charged matter) would repulse each other, thus explaining the second type of data" magical force"in scientists found in the 18th century.

Ben Franklin's idea of electricity
He was half right. It was later discovered that the use" bits of electricity" that Ben thought of turned out to be negatively charged, not positively, which was what he thought. It was also given a name-electrons, which comes from the Greek word for- you guessed it -amber.

So lots of electrons would make an object negatively charged, not positive the way Benjamin thought.
Less of it would make it positively charged.

That also explains why elecric currents go from the plus end of a battery to the minus although electrons flow from the - to the + .
In the time of Benjamin Franklin, who thought that electric currents were flows of positively charged things, defined " electric current" as flow of electricity from the + to the-
But don't blame him for thinking electrons in were positively charged -there was absolutely no way to find out if his theory was true in the time he lived.

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