Physics

Resistors Association


Parallel Association

Connecting a resistor in parallel means basically splitting the same current source so that the ddp at each point is conserved. That is:

Usually the parallel connections are represented by:

As shown in the figure, the total current intensity of the circuit is equal to the sum of the measured intensities on each resistor, ie:

By the 1st ohm law:

And by this expression, since the current intensity and voltage are maintained, we can conclude that the total resistance in a parallel circuit is given by:

Mixed Association

A mixed association consists of a combination, in the same circuit, of series and parallel associations, such as:

In each part of the circuit, the voltage (U) and current intensity will be calculated based on what is known about serial and parallel circuits, and to facilitate these calculations one can reduce or redraw the circuits using resulting resistors for each part, that is:

Being: