Metal-type resistors are one of our common resistors, usually produced from alloy wire, and have a wide range of applications. Metal resistors often need to test its resistivity during use. We have to pay attention to many things during the test. Today, let's talk about what should be noted when measuring metal resistance?

First of all, we need to know the test principle of metal resistance. According to the law of resistance, we need to know the length L of the metal wire, the diameter d (calculated cross-sectional area S) and the resistance R. We can determine the measuring instrument such as millimeter scale measuring wire length L, spiral micrometer measuring diameter d, and the required equipment with power, ammeter, voltmeter, sliding rheostat (change circuit), wire, electric keys and other equipment. Because the metal resistance is relatively small, an ampere external test is required when measuring the resistance by voltammetry.

After preparing all the equipment, we need to pay attention to the following points when testing:
1. L is the length of part of the wire to be tested between the two points of integration of the voltmeter;
  2. The metal resistivity is obviously affected by the temperature, and the power should be disconnected in time after the reading in the experiment;
  3. In order to reduce the error, the experiment reads multiple sets of U--I values for calculation, and R can take the average value or use the slope of the image to obtain;
  4, the wire diameter d, also need to use a spiral micrometer to measure the diameter of each of the three different positions, to find the average.

The above points are our considerations for measuring metal resistance. Doing these basic work allows us to test the exact resistivity, and also improve our test efficiency, ensuring that we get the accurate data we want, so that we can analyze and judge these metal resistors.