The term “resistance” is used both for the physical quantity R and for electrical components. The electrical components that have an electrical resistance and that are used in technology as components with electrical resistance are called technical resistances. They are available in very different designs and dimensions.
In the case of film resistors, a thin layer of a conductive material (e.g. carbon or metal) is vapour-deposited on an insulator. The resistance has a certain value. Such resistors with a certain, fixed value are also called fixed resistors.
In the case of film resistors, the value is attached to the resistor in the form of coloured rings as a colour code and can be read there.
The overview shown in Figure 2 shows the international colour code for resistors in the E6, E12 and E24 series.
In wire resistors (figure 3) is wound on an insulator, a wire. The electrical resistance of the wire according to the law of resistance depends on the length of the wire, its cross-sectional surface and the material of which it consists.
With adjustable resistors, a sliding or rotating contact can be used to set a different length of a resistance wire. This also changes the electrical resistance of the technical resistance, because for a metal wire, according to the law of resistance, R ~ 1 applies.