Resistors are generally referred to as resistors in daily life. It is a current limiting element, after the resistor is connected to the circuit, the resistance value of the resistor is fixed, generally two pins, which can limit the current through the branch it is connected to. If the resistance value cannot be changed, it is called a fixed resistor. Those with variable resistance are called potentiometers or variable resistors. The ideal resistor is linear, i.e., the instantaneous current through the resistor is proportional to the applied instantaneous voltage. Variable resistors for voltage division. On the exposed resistor, one or two movable metal contacts are pressed tightly. The contact position determines the resistance between either end of the resistor body and the contact.
The terminal voltage has a definite functional relationship with the current, and the two-terminal device that reflects the ability of electrical energy to be converted into other forms is represented by the letter R in ohmic Ω. Actual devices such as light bulbs, heating wires, resistors, etc., can be represented as resistor elements.
The resistance value of a resistive element is generally related to temperature, material, length, and cross-sectional area, and the physical quantity that measures the influence of resistance by temperature is the temperature coefficient, which is defined as the percentage of resistance value change for every 1°C increase in temperature. The main physical characteristic of the resistor is that it transforms electrical energy into thermal energy, which can also be said to be an energy-dissipating element, and the internal energy is generated when the current passes through it. Resistors usually play the role of voltage division and shunt in circuits. For signals, both AC and DC signals can pass through resistors.