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欧姆表测电阻简单方便,但是,由于欧姆表内部电源电动势和内阻值改变,测量引起的系统误差较大.运用比较法测电阻能大幅度地减小系统误差。一、测量方法用欧姆表测量电阻R_x时,设欧姆表的读数为R_x’,再取一阻值在所选同一挡位表盘中心值附近的标准电阻R_0用同档位测得欧姆表的读数为R_0’。则R_x/R_x’=R_0/R_0’,即R_x=R_0/R_0’R_x’。用以上方法则得R_x值比直接测得的R_x’值更接近准确电阻值。如果标准电阻选用电阻箱,测量时改变电阻箱阻值,那么,当欧姆表的读数恰好等于被测电阻的读数R_x’时,则电阻箱的阻值必等于被测电阻的阻值。
Ohm meter resistance is simple and convenient, however, due to the change of the internal power EMF and internal resistance value of the ohmmeter, the system error caused by the measurement is large. Using the comparative method to measure the resistance can greatly reduce the system error. First, the measurement method When using an ohmmeter to measure the resistance R_x, set the reading of the ohmmeter to be R_x’, and then take a resistance value that is equal to the standard resistance R_0 near the center value of the selected gear dial. Measure the ohmmeter reading with the same gear. Is R_0’. Then R_x/R_x’=R_0/R_0’, that is, R_x=R_0/R_0’R_x’. Using the above method, the R_x value is closer to the exact resistance value than the directly measured R_x’ value. If the standard resistor uses a resistance box, change the resistance of the resistance box when measuring. Then, when the reading of the ohmmeter is exactly equal to the reading R_x’ of the resistance to be measured, the resistance of the resistance box must be equal to the resistance of the resistance to be measured.