# Electrical Circuits For Dummies: Definitions, Elements, Symbols

## Electrical circuits

An electrical circuit is a collection of devices through which an electric current flows.

Consider the simplest electrical circuit. What does it consist of? It has a generator – a current source, a receiver (for example, a light bulb or an electric motor), and a transmission system (wires).

In order for the circuit to become just a chain, and not a set of wires and batteries, its elements must be interconnected by conductors. Current can only flow in a closed circuit.

Let’s give one more definition:

An electrical circuit is an interconnected source of current, transmission lines, and a receiver.

Of course, source, receiver, and wires are the simplest options for a basic electrical circuit. In reality, many more elements and auxiliary equipment are included in different circuits: resistors, capacitors, switches, ammeters, voltmeters, switches, contact connections, transformers, etc.

By the way, read about what a transformer is in a separate article on our blog. In addition, by what fundamental criterion can all electric current circuits be divided? Furthermore, by the same as the current! There are direct current circuits, and there is an alternating current.

In a direct current circuit, it does not change its direction, the polarity of the source is constant. The alternating current periodically changes in time both in direction and in magnitude. For the calculation in circuits, the use of a matrix is there. Give a shot to an online matrix multiplication calculator for easy calculations. There are different calculators available online such as determinant calculators and many more. Use according to your requirement.

### Elements of electrical circuits

All elements of electrical circuits can be divided into active and passive. The active elements of the circuit are those elements that induce EMF. These include power sources, batteries, electric motors. Passive elements are connecting wires and electrical receivers.

Receivers and current sources, from the point of view of circuit topology, are two-pole elements (two-pole devices). For their operation, they need two poles through which they transmit or receive electrical energy. Devices that carry current from source to sink are four-pole devices. To transfer energy from one two-port network to another, they need at least 4 contacts, respectively, for receiving and transmitting.

Resistors are elements of an electrical circuit that have resistance. In general, all elements of real circuits, down to the smallest connecting wire, have resistance. However, in most cases, this can be neglected and, when calculating, the elements of the electrical circuit are considered ideal.

The current-voltage characteristic is a fundamental characteristic of circuit elements. This is the dependence of the voltage at the terminals of the element on the current that passes through it. If the current-voltage characteristic is a straight line, then the element is said to be linear. A circuit consisting of linear elements is a linear electrical circuit. A non-linear electrical circuit is such a circuit, the resistance of the sections of which depends on the values ​​and direction of the currents.

### What are the ways to connect the elements of the electrical circuit?

No matter how complex the circuit is, the elements in it are connected either in series or in parallel.

When solving problems and analyzing circuits, the following concepts are used:

• A branch is a section of a circuit along which the same current flows;
• Node – connection of the branches of the chain;
• A contour is a sequence of branches that forms a closed path.

In this case, one of the nodes is both the beginning and the end of the path, and the other nodes occur in the contour only once.