时间:2011-03-11 23:18来源:蓝天飞行翻译 作者:航空 点击:次
Heat caused by the current softens the metal, and pressure on the electrodes forces the softened metal together. The current is stopped, but the pressure is held on the electrodes until the softened metal hardens. Spot welding and seam welding are types of resistance welding. resistance wire. Wire made of such alloys as Manganin or Nichrome. This wire has a high resistance and is used to make precision, wire-wound resistors and electric heater elements. resistive circuit (electrical circuit). An electrical circuit in which all of the opposition to the flow of electrons is caused by circuit resistance. In a resistive circuit, the current and voltage are in phase. resistivity (electrical characteristic). The amount of resistance for a given volume of material or for a given amount of surface area. Resistivity is the reciprocal (the opposite) of conductivity. resistor (electrical component). A component used to place a specific amount of resistance in an electrical circuit. resistor color code. A color code used to show the amount of resistance and the resistance tolerance of a composition resistor. Three or four colored bands are placed around one end of the resistor. The band nearest the end of the resistor indicates the first significant digit in the resistance. The second band is for the second significant digit. The third band shows the number of zeros to add to the two significant digits. The fourth band shows the tolerance of the resistance in percentage of the nominal value. The colors and their meanings are: resistor spark plug (ignition system component). A shielded aircraft spark plug with a built-in carbon resistor between its terminal end and center electrode. Shielded ignition leads have a metal braid around the insulator, and this braid, with the insulator and conductor, acts as a capacitor and stores electrical energy. |