時間：2011-03-11 23:11來源：藍天飛行翻譯 作者：admin 點擊：次
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Among carbon’s many important uses is that of acting as an electrical resistance element. carbon arc. An electric arc produced when current flows through ionized air from the tip of one carbon rod to the tip of another. The intense heat produced by the passage of the current causes the tips of the carbon rods to vaporize and glow with a brilliant white light. carbon black. A form of soft and fluffy carbon. Carbon black is produced by burning certain types of gas with a flame that contains insufficient oxygen for complete combustion. Carbon black is used in the manufacture of aircraft tires and as a pigment for some types of paint. carbon brake (aircraft brake). A special multiple-disk brake using pure carbon for both rotating and stationary disks. Carbon brakes are used on some high-performance aircraft because of their ability to dissipate much more energy than a metal-disk brake of similar weight. carbon dioxide (CO2). A colorless, odorless, and tasteless gas that is about 1.5 times as heavy as air. Carbon dioxide, composed of one atom of carbon and two atoms of oxygen, makes up about five hundredths of one percent of the air we breathe. Green plants take in carbon dioxide and combine it with water to make sugar. Humans and animals give off carbon dioxide in their exhaled breath. Even though carbon dioxide makes up only an extremely small part of the air we breathe, it is necessary, because it helps control our rate of breathing. Carbon dioxide is important commercially because of its use as a fire extinguishing agent. carbon dioxide fire extinguisher. A fire extinguisher that holds carbon dioxide gas under a pressure of about 800 to 900 pounds per square inch. When carbon dioxide, CO2, is sprayed on a fire, it comes out of the extinguisher in the form of a snow and blankets the fire. The snow changes into CO2 gas and pushes away all the oxygen. When there is no more oxygen to combine with the fuel, the fire goes out. carbon-film resistor (electrical component). An electrical resistor made by vacuum-depositing a thin film of carbon on a ceramic cylinder. Wires attached to each end of the carbon film allow the resistor to be connected into an electrical circuit. carbon knock (reciprocating engines). The knocking sound made in a reciprocating engine by detonation that follows preignition. Preignition occurs when incandescent (red-hot) carbon particles inside the cylinder ignite the fuel-air mixture before the engine is ready for ignition to occur. Early ignition allows the cylinder pressure and temperature to build up high enough to cause the fuel to detonate, or explode, rather than burn smoothly as it should. It is this explosion that causes the sound we hear. carbon microphone. A type of microphone used in a telephone and with some types of radio transmitters. The sensitive element in a carbon microphone is a tube of carbon granules, or grains of carbon. A flexible diaphragm acted on by sound waves presses against the carbon inside the tube. |
