時(shí)間：2011-03-11 23:13來源：藍(lán)天飛行翻譯 作者：admin 點(diǎn)擊：次
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electron volt (eV). The unit of energy that is acquired by an electron when it passes through a potential difference of one volt in a vacuum. One electron volt is equal to approximately 1.602 . 10-19 volt. electron-pair bond. Bonding of the atoms within a crystal by the sharing of valence electrons. electron spin. The rotation of an electron about its own axis. Electron spin is not the same as the rotation of an electron about the nucleus of its atom. electron transit time. The length of time required for an electron to travel between two points in an electronic device. While this time appears to be extremely short, it is an important factor in designing high-speed electronic computers. electron tube. The correct term for an electronic component which normally goes by the name of vacuum tube or valve. An electron tube is a form of electron control valve. Electron tubes have a heated cathode that emits electrons and an anode, or plate, connected to a high positive voltage that attracts the electrons. The flow of electrons between the cathode and the anode is controlled by the voltage on one or one more grids placed between the cathode and anode. The cathode and its heater, the grids, and the anode, are all housed inside a glass or metal envelope from which all the oxygen has been removed. The envelope may be left with a vacuum, or it may be filled with an inert gas. electroplating. A method of coating one kind of metal with another. Cadmium is often plated on steel to make it corrosion resistant, and chromium can be plated on steel to make it hard and wear resistant. The steel is connected to the negative terminal of a direct current power supply, the cadmium or chromium is connected to the positive terminal, and both metals are immersed in an electrolyte. Ionized atoms of cadmium or chromium in the electrolyte are deposited on the steel, and these atoms are replaced from the cadmium or chromium electrode. electropolishing. The production of a smooth finish on a piece of metal by submerging it in a suitable electrolyte and making it the anode in an electrolytic process. The surface roughness is electrolytically removed. electrostatic charge. An electrical charge that can exist on the plates of a capacitor or on an insulated object. A negative electrostatic charge is caused by an accumulation of electrons, and a positive charge is caused by a lack of electrons. electrostatic deflection. A method of controlling the position of a beam of electrons on the face of a cathode-ray tube. The beam of electrons that forms the trace on a cathode-ray tube may be deflected to the correct position on the screen by electrostatic charges on plates placed above and below the beam, and on each side of the beam. If, for example, the top plate is given a positive charge, and the bottom plate a negative charge, the electrons in the beam (all electrons are negative) will deflect away from the lower plate toward the upper plate. The beam will deflect upward. |
