A resistor is a two-terminal electronic component made of resistive material with a certain structural form that can limit the flow of current in a circuit. The resistance value of a resistance element is generally dependent on temperature, material, length, and cross-sectional area. The physical measure of resistance affected by temperature is the temperature coefficient. The resistor is generally used to regulate and stabilize the current and voltage in the circuit. According to the circuit requirements, resistors can also be used to amplify the circuit negative feedback or positive feedback, voltage-current conversion, input overload voltage or current protection elements.
Resistors can be divided into three categories: fixed resistors, potentiometers and sensitive resistors. A sensitive resistor’s value is sensitive to a certain physical quantity(such as temperature, humidity, light, voltage, mechanical force, etc.). When these physical quantities change, the resistance value of the sensitive resistor will change with the physical quantity, presenting different resistance values.