Electric current

Introduction to electricity: concepts and definition

Introduction to electricity: concepts and definition

Electricity is a fundamental force in our modern world, powering a wide range of devices and systems we use in our daily lives. From lighting our homes to operating our electronic devices, electricity plays a crucial role in today's society.

In this section, we will provide an introduction to electricity, analyzing what it is, the basic concepts that govern it, the types of electricity that exist, and the fundamental laws that govern it.

What is electricity?

Introduction to electricity: concepts and definitionElectricity is a form of energy resulting from the presence and movement of charged particles, whether electrons or ions. These charged particles generate an electric field that exerts a force on other charged particles, thus creating the possibility of doing work.

This energy manifests itself in various forms, including the kinetic energy of moving electrons, potential energy stored in electric and magnetic fields, and thermal energy released in the resistance of materials.

Electricity Basics

To better understand this phenomenon, it is important to familiarize yourself with some basic concepts :

Electric charge

Electricity originates due to the presence of electrical charges. There are two types of electric charge : positive and negative. Opposite charges attract, while like charges repel. Electrons have a negative charge, while protons have a positive charge.

Electric current

Electric current is the flow of electrons through a conductor, such as a wire. It is measured in amperes (A) and its direction is conventionally established from the positive to the negative pole.

Electrical current is what allows electricity to flow through circuits and power devices.


Voltage, measured in volts (V), represents the difference in electrical potential between two points in a circuit.

The higher the voltage, the greater the driving force for electrons to move in the circuit. Voltage is responsible for the ability of a circuit to do work.


Electrical resistance, measured in ohms (Ω), is the property of a material or component that opposes the flow of electric current. The larger the resistance, the lower the current in the circuit.

Ohm's law states that current is directly proportional to voltage and inversely proportional to resistance.

Electric power

Electrical power, measured in watts (W), is the amount of electrical energy consumed per unit of time. It is the product of voltage and current in a circuit (P = VI).

Power is an important factor in determining the performance and efficiency of electrical devices.

Types of electricity

Electricity can be classified into two main types:

Static electricity

Introduction to electricity: concepts and definitionStatic electricity is the result of the buildup of electrical charges on an object, usually due to friction.

A common example is when a person rubs their feet on a rug and then touches a metal object, feeling an electric shock. Lightning during a storm is also an example of large-scale static electricity.

Dynamic electricity

Dynamic electricity is the flow of electrical charges in an electrical circuit, as found in most electrical applications. It is subdivided into two types:

Direct current (DC)

Direct current is a constant, unidirectional flow of electrons through a circuit.

Batteries supply direct current, and are commonly used in applications such as consumer electronics and emergency power systems.

Alternating current (AC)

Alternating current changes its direction of flow at regular intervals. This is accomplished using electrical generators and is the form of electricity used in most homes and long-distance power transmission systems.

Alternating current is especially efficient in transmitting electrical energy over long distances.

Fundamental laws of electricity

To understand and use electricity effectively, it is essential to know some of the fundamental laws that govern its behavior:

Coulomb law

Coulomb's law states that the force between two electric charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them. This law is fundamental to understanding how charges interact with each other.

Ohm's law

Introduction to electricity: concepts and definitionOhm's law, mentioned above, states that current in a circuit is directly proportional to voltage and inversely proportional to resistance. Mathematically, it is expressed as V = IR, where V is the voltage, I is the current and R is the resistance.

Kirchhoff's Law

Kirchhoff's laws are two fundamental rules that govern the conservation of charge and energy in electrical circuits.

  • Kirchhoff's law of currents states that the sum of the incoming currents at a node is equal to the sum of the outgoing currents.

  • Kirchhoff's voltage law states that the sum of the voltage drops in a closed circuit is equal to the sum of the applied voltages.

Faraday's law of electromagnetic induction

Faraday's law of electromagnetic induction states that a change in magnetic flux through a surface induces an electric current in a nearby circuit. This law is the basis of electricity generation in generators and transformers.

Electricity example: solar energy

Introduction to electricity: concepts and definitionPhotovoltaic solar energy is an extraordinary example of how electricity can be generated in a sustainable and renewable way from an inexhaustible source: the sun. This process is based on the photovoltaic effect, which is the ability of certain materials, such as solar cells, to convert sunlight into electricity.

When photons from sunlight hit solar cells, they release electrons in a process that generates an electrical potential difference, thus creating an electric current. These solar cells are grouped into photovoltaic panels that can be installed on rooftops or in large fields, converting solar energy into usable electricity.

Electricity generated from solar energy is clean, renewable and sustainable, with no greenhouse gas emissions. This example demonstrates how electricity can be produced in an environmentally friendly manner, reducing dependence on fossil fuels and contributing to climate change mitigation.


Electricity is a fundamental force that powers much of our modern world. Understanding the basic concepts, types and laws that govern it is essential to harness its potential in practical applications.

Whether it's the static electricity that creates sparks on a dry day or the dynamics that power our homes and devices, electricity plays a crucial role in our daily lives and in the advancement of technology.

Publication Date: May 20, 2019
Last Revision: October 26, 2023