Scientific Seen

News, Commentary, and Tutorials from a Scientific Perspective

Maybe you’ve made your own cheese, or installed a solar panel, or you’re filtering seawater for your aquarium. Anytime you have some kind of physical process in place, you’d probably like to monitor it so you know what’s going on and you know when you’re having a problem. With your own monitoring system, you can measure temperature, current, salinity, or just about anything else you need to track with digital panel meters. But you need to know the reading displayed is accurate. That’s why you calibrate your meter.

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Originally published in eHow, OCT 2011

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Nearly everything that uses electrical power has semiconductor circuits: your car, your coffeemaker, your computer. The performance of those circuits stems from the behavior of electrons within an ordered array of atoms, or a crystal lattice. Usually, the lattice is made from a base material of silicon atoms, with “dopants” added to increase or decrease the number of electrons in the material.

“N-type” semiconductor is made by introducing a dopant such as phosphorus, which brings extra electrons, whereas “p-type” has a dopant such as boron, which reduces the number of electrons compared to the base material. The interesting properties take place at the junction, where n- and p-type materials are brought into contact with one another. One of the things that happens is that the extra electrons from the n-type make their way to the p-side, and the missing electrons from the p-side, called “holes,” make their way to the n-side. The region in between is emptied of charge, hence the name “depletion region.”

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Originally published at eHow, SEP 2011

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Fire is hypnotic. Sit any group of campers around a nighttime fire, and you’ll notice their attention drawn by the constantly shifting interplay of form and color. Observing the sun offers that same fascination, enhanced by the knowledge that the flames of the sun support all life on Earth. The roiling, popping, swirling outer surface of the sun is best seen with one particular narrow part of the spectrum, the hydrogen alpha line, which is one particular wavelength of red light. The wavelength is 656.28 nanometers, or 656.28 billionths of a meter. The principles behind a filter that will isolate that wavelength are clear.

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Originally published at eHow, SEP 2011

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Every system that transmits information has some kind of speed limitation. The speed limitation is characterized by the bandwidth. One way of characterizing the bandwidth of a system is by observing its response to a pulse. As with any communications link, there are two ends: a sender and a receiver, and the measured speed will be due to characteristics at both ends. The best way to characterize such a system is by doing a measurement by which one end of the measurement system is known to be very fast.

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Originally published at eHow, SEP 2011

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Fusion reactions at the core of the sun power a circulating flow of incredible energies that culminate in the emission of tremendous amounts of electromagnetic radiation. The spectrum of the sun generally follows what’s known as a blackbody spectrum, which contains a certain amount of power across a spectral region stretching from ultraviolet to infrared. The form of the blackbody radiation makes it a relatively straightforward process to calculate the solar flux density that strikes Earth.

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Originally published at eHow, SEP 2011

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