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frequency changes if refrigerant gas is picked up in its sensor tube. The sensor tube is held below a
suspected leak, and if any refrigerant is leaking, the sound produced by the oscillator will change from a
low tone to a high-pitched squeal. Electronic leak detectors can detect a leak as small as a few parts of
refrigerant gas in a million parts of air.
electronic oscillator. An electronic circuit that converts DC electricity into AC electricity.
electronics. The study and use of the movement of free electrons. In electricity, we normally think of the
movement of electrons only through conductors; but in electronics, we also consider the movement of
electrons through materials that are not always conductors. Electrons can be caused to flow through a
vacuum and through semiconductor materials such as silicon and germanium.
electronic voltmeter. A special type of electronic instrument used to measure voltage. Electronic
voltmeters use electron tubes or solid-state components, such as field-effect transistors (FET), to amplify
the voltage being measured before it is read by the indicating instrument.
An electronic voltmeter has a much higher input impedance than a nonelectronic meter, and it can
measure AC voltages having a wider range of frequencies.
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.
Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
Page 222
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.
electrostatic energy. Energy stored by an electric stress in the dielectric of a capacitor when two opposing
electrical charges act across the dielectric. When a battery is connected across the two plates of a capacitor,
electrons are pulled from one plate and forced into the other. When all the electrons that can be moved by
the battery have been moved, the capacitor is charged and no more current flows. The battery can be
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航空术语词典Dictionary of Aeronautical Terms 中(19)
