When electric components are connected to each other to obtain a certain result, an electronic circuit is made. Electric circuits can be outlined by using a correct symbolism for its components and the electric quantities involved. Every component reacts according to certain rules to the electric quantities that stimulate them; through electronic schemes and the formulas associated to them, it is possible to have complete control on the functions of the circuit in question. In the following circuit we'll be highlighting how the application of tension to the extremities of a resistance generates current-flow through it.
Let's now take a look at a series of simple circuits. They are nevertheless important, the more complicated circuits being expansions and elaborations of these simpler examples.
Series circuit: In this type of circuit the current-flow passes fully through each of the resistances:
Circuit with resistors in series
The entire circuit has a total resistance value equalling the sum of the resistances in series:
Equation 4.8. Equivalent resistance of two resistors in series
We can notice how the total value increases when the resistances increase.
Parallel circuits: In this kind of circuit, the current-flow is sub-divided into various parts each of which flows into one of the resistances. The lower the resistance, the greater the amount of the current-flow that flows through it:
Parallel resistance circuit
The whole circuit has an equivalent resistance, given by the following formula:
Equation 4.9. Equivalent resistance of two parallel resistors
In other words, the total value decreases as the number of parallel resistors increase.
Resistance partitor: This type of circuit is used when we need to sub-divide tension into smaller tensions:
Resistance partitor
Equation 4.10. Formulae that describe the Resistance partitor
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Simple circuit