The role of its basic electronic components is to impede the flow of electric current. The two basic parameters to measure resistors are resistance and power. Resistance is used to denote the magnitude of the impediment effect of resistors on current. It is expressed by Ohm. In addition to the basic units, there are thousands of Europe and mega. The power is used to express the larger current that the resistor can bear. In Watt, there are many kinds of 1/16W, 1/8W, 1/4W, 1/2W, 1W, 2W and so on. The resistor will burn out over this larger value. According to the different materials of the resistor, there are cement resistors (low production cost, high power, high thermal noise, low resistance, unstable work), carbon film resistance, metal film resistance (small volume, stable work, low noise, high precision), and metal oxide film resistance and so on. According to whether the resistance is changeable, it can be divided into fine tuning resistor, adjustable resistor, potentiometer, etc.