Resistance of the site of a chain depends, first of all, on the fact that represents this site of a chain. Both the usual resistive element, and the condenser or the coil of inductance can be it.

## Physical quantity resistance

Resistance of the site of a chain is determined by a ratio of Ohm's law for subcircuit. The law of Ohm determines element resistance by the relation of tension enclosed to it to force of the current passing through an element. But thus resistance of the line section of a chain, that is the site through which current linearly depends on tension on it is defined. If resistance changes depending on value of tension (and current, respectively), then resistance is called differential and is defined derivative function of tension from current.

## Scheme of the site of a chain

Current in a chain is created by moving charged particles which electrons most often are. The more a scope for movement have electrons, the more there is a conductivity. Present that this site of a chain consists not of one element, and of several, connected in parallel with each other. Conductivity electrons, moving on an electrical circuit and approaching the site in parallel of the connected elements, are divided into several parts. Each component passes through one of site branches, forming in it own current. Thus, increase in number in parallel of the connected conductors reduces the full resistance of the site, giving to electrons additional ways for the movement.

## Resistance of resistors

The physical nature of effect of resistance in case of resistive elements is based on collision of charged particles with ions of a crystal lattice of substance of the conductor. The more collisions, the resistance is more. Therefore, resistance of the site of a chain formed by a resistive element depends on its geometrical parameters. In particular, increase in length of the conductor conducts to the fact that a smaller part of electrons, moving ahead on the conductor, manages to reach its opposite pole, as leads to decrease in resistance. On the other hand, increase in cross-sectional area of the conductor gives more space for the movement of electrons of conductivity and allows to reduce resistance size.

## Resistance of capacity and inductance

In case of consideration of the site of a chain which is capacitive and inductive elements it is influenced important frequency parameters. It is known that the condenser does not carry direct electric current, however, if alternating current, then resistance of the condenser is quite concrete. The same concerns also inductive elements of a chain. If the dependence of resistance of the condenser on current frequency inversely proportional, then same dependence at the coil of inductance is linear.