凯尔文电桥实验的分析

Analysis of Kelvin bridge experiment

在凯尔文电桥中,待测电阻端和标准电阻端也存在接触和引线电阻,然而这些接触和引线电阻很少被关注且对电阻测量的影响一直不清楚。研究了凯尔文电桥中并入待测电阻端和标准电阻端的接触和引线电阻对测量结果的影响并给出了减小影响的方法。研究发现:凯尔文电桥的倍率大于1时,测量值的误差随倍率的增大而增大;另外,倍率小于1时,测量值的误差随倍率的增大而减小;最后,倍率约等于1时,测量值的误差最小。研究表明:采用倍率约为1的电桥,并入待测电阻端和标准电阻端的接触和引线电阻可以近似不影响测量结果。

In Kelvin bridge,there are also contact and lead resistances at the measured resistance and standard resistance ends,but these contact and lead resistances have received little attention and their influence on resistance measurement has always been unclear.In this paper,the influence of the contact and lead resistance,incorporated into the measured resistance and standard resistance ends of the Kelvin bridge,on the measurement result is studied and the method to reduce the influence is proposed.The study finds:when the magnification of the Kelvin bridge is greater than 1,the error of the measured value increases with the increase of the magnification;in addition,when the magnification is less than 1,the error decreases with the increase of the magnification;finally,when the magnification is about 1,the error is the smallest.The study shows that the contact and lead resistances,incorporated into the measured resistance and standard resistance ends,can be approximated without affecting the measurement result by using the bridge with a magnification of about 1.