Composition of resistor:
A two terminal electronic component made of resistance material and having a certain structure, which can limit the current passing through the circuit. A fixed resistor is called a fixed resistor. Variable resistance is called a potentiometer or variable resistor. The ideal resistor is linear, that is, the instantaneous current passing through the resistor is proportional to the applied instantaneous voltage. For some special resistors, such as thermistor, varistor and sensitive element, the relationship between voltage and current is nonlinear. Resistor is one of the most widely used components in electronic circuit. It usually forms different series according to power and resistance value for circuit designer to choose.
Resistor is mainly used to adjust and stabilize the current and voltage in the circuit. It can be used as shunt and voltage divider, as well as circuit matching load. According to the requirements of the circuit, it can also be used for negative feedback or positive feedback, voltage current conversion, voltage or current protection element when input overload, and RC circuit can be used as oscillation, filtering, bypass, differential, integral and time constant components.
Function of resistor:
Low power resistors are usually made of carbon film encapsulated in a plastic shell, while high-power resistors are usually wound resistors, which are made by winding metal wires with high resistivity around the ceramic core.
If the resistance of a resistor is close to zero ohm (for example, a large cross-section wire between two points), the resistor has no blocking effect on the current, and the circuit of the resistor in parallel is short circuited and the current is infinite. If a resistor has infinite or large resistance, the circuit connected in series can be regarded as an open circuit with zero current. The resistor commonly used in industry is between two extreme cases. It has a certain resistance and can pass a certain current, but the current is not as large as that in short circuit.
The current limiting effect of the resistor is similar to that of the small-diameter pipe connected between two large-diameter pipes to limit the water flow. Resistance, usually abbreviated as R, is a basic property of conductor, which is related to the size, material and temperature of conductor. Ohm's law says that if I = u / R, then r = u / I, the basic unit of resistance is Ohm, which is represented by the Greek letter "Ω". There is such a definition: when a voltage of one volt is applied to a conductor, the resistance value corresponding to an ampere current will be generated. The main function of a resistor is to block the flow of current. In fact, "resistance" refers to a kind of property, and the resistance usually referred to in electronic products refers to such a component as resistor. Ohm is often referred to as Europe. The common units of resistance are kilo ohm (K Ω), megaohm (m Ω), and milliohm (m Ω).