Mixed electric circuits (series – parallel)

26/02/2026

The online mixed circuit simulations on this page allow you to explore how the series and parallel parts are combined and behave within the same circuit. Through virtual setups with a power source, switch, bulbs, resistors, ammeters, and voltmeters, you can analyze how current and voltage are distributed in each section and how to calculate the equivalent resistance by simplifying the circuit step by step.

What are mixed electric circuits

Mixed circuits combine series and parallel sections within one setup. This structure allows some parts of the circuit to share the same current, as in the series sections, while other branches have independent paths for current flow, as in the parallel sections. To analyze these circuits, you first identify the series and parallel sections, calculate the equivalent resistance for each part, and then simplify the circuit step by step. This type of configuration is very common in real-world setups and serves as a bridge between simple circuits and the analysis of more complex electrical systems.

How to identify series and parallel sections

In a mixed circuit, the first step is to visually distinguish which components are in series and which form parallel branches. Two elements are in series when the current can only advance by passing through them one after the other, with no split between them. On the other hand, components are in parallel when the conductor divides into two or more independent paths that later rejoin. Recognizing these structures allows you to break down the circuit into simpler blocks and apply the rules you already know for series and parallel circuits to each section. This initial identification is essential for correctly analyzing the behavior of the complete circuit.

How to calculate equivalent resistance in a mixed circuit

The calculation of equivalent resistance in a mixed circuit is done by simplifying the setup in parts. First, you identify the sections that are clearly in parallel and replace them with their equivalent resistance. Then you add the resistances that remain in series. This process is repeated successively until the entire circuit is reduced to a single total resistance. This step-by-step method allows you to analyze setups that may seem complex at first glance and understand how each section affects the overall behavior of the circuit.

To carry out these simplifications, it is necessary to remember the basic formulas for each type of connection:

Resistances in series

Req = R₁ + R₂ + R₃ + … + R_n

Resistances in parallel

1/R_eq = 1/R₁ + 1/R₂ + 1/R₃ +…+ 1/R_n

These two rules let you break down any mixed circuit in stages and obtain its equivalent resistance in an organized way.

How current and voltage are distributed in a mixed circuit

In a mixed circuit, the rules for series and parallel circuits are combined. In the series sections, the current is the same in all components and the voltage is divided according to the value of each resistance. In the parallel sections, the opposite occurs: the voltage is the same across all branches and the current is split among them. Analyzing a mixed circuit involves applying these two rules in an orderly fashion, section by section, to determine how the current flows and how the voltage is distributed in each part of the circuit. This analysis allows you to understand the functioning of real electrical setups, where both configurations are often combined.

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Simulations of mixed electrical circuits

Basic mixed electric circuit

This simulation shows a circuit with one series resistance and two parallel branches: one with a resistor and the other with a bulb. Ammeters let you see how the current is the same in the series section and divides when it reaches the parallel branches. The voltmeter lets you check that the voltage is the same in both branches and measure the drop across the series resistance. This is a brief and clear activity to introduce how series and parallel combine in a mixed circuit.

Circuit with two parallel branches with internal series sections

This simulation presents a mixed circuit consisting of an external series resistance and two parallel branches with different internal configurations. One branch contains a bulb and two resistors in series, creating a path with a high total resistance. The other branch has two resistors in series, forming a simpler path but with its own resistance to current flow. This difference between branches allows you to see how the current divides unevenly in the parallel section, since each path offers a different total resistance. Ammeters let you compare the current in each section, while the voltmeter lets you measure the voltage between different points in the circuit. This setup is designed to help you understand how several levels of series and parallel can be combined within a single mixed circuit and how each section affects the overall behavior.

CCircuit with two parallel branches with internal series sections

Comparison between a mixed circuit and its equivalent resistance

This simulation presents two circuits placed side by side to directly observe how the equivalent resistance formulas work in mixed circuits. The first circuit includes an external resistance and two parallel branches, each with its own total resistance. The second circuit is much simpler: it contains only a single resistor, whose value can be adjusted to match the equivalent resistance calculated from the mixed circuit. This setup allows you to see that, when the resistance of the simple circuit matches the equivalent resistance of the complex circuit, both show the same total current for the same applied voltage. This activity is designed to experimentally verify that different internal configurations can behave electrically equivalent when their total resistance is the same, reinforcing the concept of equivalence between circuits.

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“If I have seen further, it is by standing on the shoulders of giants”

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1775

–

1836

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“Science is the explanation of the complex by the simple”

James Clerk Maxwell

1831

–

1879

James Clerk Maxwell formulated Maxwell’s equations, unifying electricity and magnetism and predicting electromagnetic waves

“Thoroughly conscious ignorance is the prelude to every real advance in science”

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Giants of science

“If I have seen further, it is by standing on the shoulders of giants”

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James Clerk Maxwell formulated Maxwell’s equations, unifying electricity and magnetism and predicting electromagnetic waves

“Thoroughly conscious ignorance is the prelude to every real advance in science”

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