Modern Physics

Parallel circuit: features, how it works and examples

A parallel circuit is the scheme in which electrical current is distributed in several branches throughout the assembly. In these circuits the elements are located in parallel; that is, the terminals are connected between equals: positive to positive and negative to negative.

Thus, the voltage across each parallel element is exactly the same across the entire configuration. The series circuit consists of several circulation loops, formed by the presence of nodes. The current intensity is divided into each branch depending on the energy demand of the connected loads

Parallel circuit: features, how it works and examples 1


These types of circuits have a parallel connection, which implies certain properties intrinsic to this type of scheme. The main features of parallel circuits are described below:

The element terminals are connected in parallel.

As the name implies, the connections of all receivers match at the input and output terminals. This means that the positive terminals are connected together, as are the negative terminals.

Voltage is the same between all terminals in parallel.

All circuit components connected in parallel are subject to the same voltage level. That is, the tension between the vertical nodes is always the same. Thus, the equation that expresses this characteristic is as follows:

Parallel circuit: features, how it works and examples 2

When connecting batteries or batteries in parallel, they maintain the same voltage level between the nodes as long as the polarity connection (positive positive, negative negative) is appropriate.

This configuration has the advantage of uniform consumption of the batteries that make up the circuit, so that the useful life of each one of them is considerably longer.

The total intensity of the circuit is the sum of the currents from all branches.

The current is split at all nodes it crosses. Thus, the total system current is the sum of all branch currents.

Parallel circuit: features, how it works and examples 3

The inverse of the total resistance of the circuit is the sum of the inverse of all resistors.

In this case, the sum of all resistances is given by the following algebraic expression:

Parallel circuit: features, how it works and examples 4

As more resistors are connected to the circuit, the lesser is the total equivalent resistance of the system; and if the resistance decreases, the intensity of the total current is greater.

The components of the circuit are independent of each other.

If any of the nodes in the circuit are not incorporated or some electronic components melt, the rest of the circuit will continue to work with the connected branches that remain connected.

Parallel connection, in turn, facilitates the independent activation or disconnection of each branch of the circuit, without necessarily affecting the rest of the assembly.

How it works?

A parallel circuit works by connecting one or several power sources, which can be connected in parallel and provide electrical power to the system.

Electric current flows through the circuit and bifurcates as it travels through the nodes of the assembly – through the various branches – depending on the energy demand of the components located in each branch.

The main advantage of parallel circuits is the robustness and reliability of the system, since if one of the branches is disconnected, the others continue to function as long as they have a power source.

This mechanism makes parallel circuits highly recommended in complex applications where it is necessary to have a backup mechanism to always guarantee the overall system operation.

How to do it?

The assembly of a parallel circuit is more elaborate compared to a series circuit, given the multiplicity of ramifications and the care that must be taken with the connection of the terminals (+/-) of each element.

However, replicating an assembly of this nature will be an easy task if you follow the following instructions to the letter:

1- Place a wooden board as the base of the circuit. This material is suggested due to its dielectric properties.

2- Locate the circuit battery: keep a standard battery (9 Volts, for example) at the base of the circuit using insulating tape.

3- Place the switch close to the positive polarity of the battery. In this way, you can turn on or stop the flow of current through the circuit, turning off the power source.

4- Place two lamp holders parallel to the battery. The lamps connected to these elements will act as circuit resistances.

5- Prepare the circuit conductors, cutting the cables according to the distances between the circuit elements. It is important to remove the conductor coating at both ends to ensure direct copper contact with the terminals of each receiver.

6- Make connections between circuit components.

7- Finally, press the switch to check the lighting of the lamps and, consequently, the correct functioning of the circuit.


The vast majority of domestic applications – such as the internal circuits of a washing machine or heating system – are precisely parallel circuits.

Residential lighting systems are also connected in parallel. That’s why, if we have several bulbs inside a light fixture and one burns out and leaves the branch out of service, the other bulbs can maintain their operation.

Parallel connections allow multiple plugs to be connected independently, so users can choose what to connect and what not, as all applications need to be connected simultaneously.

Parallel circuits are ideal for domestic and residential applications as they maintain the voltage level between all nodes in the circuit.

This ensures that equipment that works at a specific voltage (110V – 220V) has the necessary voltage level to operate satisfactorily.

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