时间：2011-03-11 23:13来源：蓝天飞行翻译 作者：admin 点击：次
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Lenticular clouds are an indicator of extreme turbulence. Lenz’s law (electrical law). The electrical law explaining induced current. Lenz’s law states that the current induced in a conductor cut by lines of magnetic flux flows in the direction opposite to that of the current which produced the lines of flux. level (horizontal condition of a body). A flat, horizontal surface of a body is said to be level when all points on the surface are perpendicular to a line which points directly toward the center of the earth. level (spirit level, or bubble level). An indicating device used to show a level condition. A curved glass tube is almost, but not completely, filled with a clear liquid, and since the tube is not entirely full, there is a small air bubble in the liquid. This bubble, being much lighter than the liquid, always rises to the highest point in the tube. The curved tube is mounted in a long straight bar, or housing, in such a way that the bubble rises to the center of the tube when the housing is perpendicular to the pull of gravity (perpendicular to a line pointing to the center of the earth). leveling lugs (aircraft component). Brackets or other structural devices installed in an aircraft in such a way that when the aircraft is in its level-flight attitude, a straightedge placed across the lugs will be level. leveling means (aircraft specification). The method specified by the aircraft manufacturer to determine the level-flight attitude of an aircraft. The leveling means may require the use of a spirit level or a plumb bob. level of free convection (meteorology). The level at which a parcel of air lifted dry-adiabatically until it becomes saturated, and then moist-adiabatically would become warmer than its surroundings in a conditionally unstable atmosphere. lever. A rigid bar, free to pivot, or rotate about a point called the fulcrum with an input force applied to one point, and an output force taken from another point. The lever, one of the simple machines like the wheel, screw, and inclined plane, can be used to change a force or the speed of movement. The action of a lever is determined by the placement of the fulcrum and by the distance between the fulcrum and the points the force is put into and taken from the lever. See first-class lever, second-class lever, and third-class lever. levitate. To suspend an object in the air in such a way that it appears to disobey the law of gravity. A magnetic body can be levitated by suspending it in a strong magnetic field. Leyden jar. One of the earliest examples of an electrical capacitor. A Leyden jar is a glass container with a liner of metal foil pressed against its inside surface and a coating of metal foil on the outside of the jar. When a source of DC electricity is connected across the two pieces of foil, electrostatic energy is stored in the glass (the dielectric of the capacitor). liaison aircraft. A type of light military aircraft made popular during World War II because of its ability to land and takeoff from unimproved terrain. Liaison aircraft have been replaced by helicopters. |
