What is resistance? Generally speaking, resistance plays the same role in the circuit as the resistance encountered in water flow. The resistor is to achieve a specific purpose by consuming electricity and distributing the current in the circuit. Resistors have a wide range of functions in electronic circuits. Resistors can not only be used alone, but also form circuits with various functions together with other components.

For conductors, the existence of resistance makes the current flow encounter resistance. The specific performance is that the resistance consumes electric energy. Obviously, in this sense, the role of resistance is dissipation. However, using this characteristic of resistance in the circuit can play many specific circuit functions.

There are many types and forms of ordinary resistors, including high-frequency metal film resistors, high resistance glass glaze resistors, high resistance metal film resistors, metal film resistors, precision metal film resistors, cement resistors, oxide film resistors, fuse resistors, chip resistors, etc.

In terms of fixed resistors, fixed resistors mean that the resistance of the product is fixed. It is mainly divided into carbon film resistors, metal film resistors, wound resistors, thermistors, photosensitive resistors, varistors, etc.

Carbon film resistor (RT): first coat a layer of carbon resistance film on the magnetic rod or porcelain tube according to certain process requirements, then install caps on both ends, weld leads, apply protective paint on the surface, and finally print technical parameters. It is characterized by good stability, low production cost, low price and wide resistance range.

The shape of metal film resistor is similar to that of carbon film resistor, but the metal film is made by vacuum evaporation or burning infiltration on the surface of magnetic rod or ceramic tube, such as nickel chromium alloy film and gold platinum alloy film. It is characterized by better stability, higher accuracy, lower noise, wider resistance range and higher heat resistance compared with carbon film resistance.

The main technical indicators of resistors, the most important of which include two aspects:

Rated power; The rated power of the resistor is the maximum power that is allowed to be consumed by the resistor when it works continuously for a long time without damage or significant change in its performance.

Nominal resistance: resistance range and resistance with different accuracy change with its series..