Once upon a time, there were two pieces of crystal silicon. The negatively charged electrons inside were very happy, snuggled in positively charged “holes.” This made the crystal silicon happy and neutral on all matters electric.
One day, a physicist took the two pieces and “doped” them, which is to say she {my physicists are always girls} coated each of them with a solution of phosphorous and boron, respectively. Now phosphorous has an abundance of electrons, while boron has too few. Suddenly, the crystal silicon pieces were unbalanced and decidedly on opposing sides: the sides of N {negative} and P {positive}.
The physicist then put the two pieces together with a thin wafer of N Type silicon between, creating a junction. The homeless electrons were eager to cross the border and jump into the P Type silicon. There was a mad rush, and the realtors worked overtime as electrons found new holes and moved in. However, the rush had an interesting, and as yet unforeseen, effect. As a metropolis sprung up, something began to occur on the junction: an electric field. A diode, if we are being particularly scientific.
No electron could have said what havoc this diode would cause. No electron foresaw the coming sunlight.
Sunlight is made of energy. Little packets of energy, called photons. They come in varying amounts, but, when the amount is just right, they are particularly adept at shaking electrons out of their little holes. They are hot, bright packets of pure earthquake.
The physicist put the crystal silicon in sunlight. {Well, she actually used a synthetic light. But that is not half as interesting.} The photons arrived.
The electrons could not withstand the shaking and bounced out of their holes. And this was when the effects of the diode were fully felt. The diode grabbed the shaken electrons and pushed them toward the N Type silicon, where all the holes were filled. As for the now-empty holes, the diode slid them toward the P Type silicon. It is safe to say that the real estate market crashed.
But the physicist had a shred of pity--or science--in her heart. She connected the N Type silicon, with its abundance of clamoring, homeless electrons, to a P Type metal. With a cheer, the electrons hurried towards it and all the new holes that awaited them.
Their journey took place on a wire. The physicist monitored it carefully, for the speed of the electrons was something called a Current. This Current was directly related to the number of electrons that passed by per second. And as the electrons left their holes behind, not knowing that the holes were taking a similar journey away from the P Type silicon, the difference between positive and negative charge grew--this was something called Voltage.
Voltage multiplied with Current equals Power.
It would not be quite accurate to say that the physicist attached both wires to a light bulb and filled the room with light. She is not an engineer, she is a resesarch experimentalist, and so she simply connects things to a computer and watches the graph of Current vs. Voltage take shape.
But in the interest of artistic license, she attached the wires to a light bulb, created a closed circuit, and smiled in the soft yellow glow of successful science.
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