What is electricity?

Electricity is a set of phenomena produced by the movement and interaction between the positive and negative electric charges of physical bodies.

The word ‘electricity’ comes from the Latin electrum, and in turn from the Greek élektron, or amber. The reference to amber comes from a discovery recorded by the French scientist Charles-François de Cisternay du Fay, who identified the existence of two types of electrical charges (positive and negative). Positive charges were manifested by rubbing glass, and negative charges by rubbing resinous substances such as amber.

The energy produced by electrical charges can manifest itself in four domains: physical, luminous, mechanical, and thermal.

While electricity is abstract or ‘invisible’ in most of its manifestations, such as in the human nervous system, it is sometimes possible to ‘see’ it, such as lightning when a severe thunderstorm develops.

Electricity is a secondary energy source

Primary energies are those obtained directly from nature: solar, hydraulic, wind, geothermal, biomass, oil, natural gas, or coal.

Secondary energies come from the transformation of primary energy for direct consumption or for other uses: petrol, electricity, diesel, fuel oil, etc.

How is electricity produced for consumption?

Electricity is produced by electricity systems that guarantee its availability.

An electricity system is the set of elements that operate in a coordinated manner in a given territory to satisfy the consumers' demand for electricity.

Electricity systems can be classified as follows:

• Generation centres or plants where electricity is produced (nuclear, hydroelectric, combined cycle, wind farms, etc.).
• High-voltage (HV) electricity transmission lines.
• Transformer stations (substations) that reduce the voltage or voltage of the line (high voltage / medium voltage, medium voltage / low voltage).
• Medium and low voltage distribution lines carry the electricity to the points of consumption.
• An electrical control centre from which the power generation and transmission system is managed and operated.

Uses and applications of electricity

Electricity is an indispensable source of energy. In every household, there are all kinds of appliances and domestic appliances that run on electricity, as well as the lighting system.

In industry, almost half of the energy consumed is electrical. Electricity is used both as a driving source for the electric motors of the machines and appliances in each sector, and to heat the contents of tanks, reservoirs, and boilers. As in the domestic sector, electricity is also the main lighting source, providing heating and cooling for air-conditioning equipment.

The tram, metro, or train is the means of electric transport par excellence. Currently, electric vehicles are being designed mainly for urban use, as well as so-called ‘hybrid’ vehicles in which the electric motor is combined with an internal combustion engine, thus enjoying the advantages of both energy sources. The battery can be recharged by simply plugging it into an electrical socket.