The material consists of atoms.
Each atom is composed of:
Of a central nucleus which is an assembly of protons and neutrons;
The protons carry positive charges and the neutrons do not carry charges and are therefore neutral (hence their name);
Of a set of electrons which turn very fast around this nucleus;
The electrons carry negative charges.
Normally, an atom comprises as many electrons as protons, so as many positive charges as negative charges.
These charges balance, making the atom electrically neutral.
But it is enough that an electron is added to those of this atom (by friction with another atom for example) so that the equilibrium is broken and the atom becomes negative. In the same way, it is enough that an electron is removed at this atom so that the atom becomes positive.
Electricity results from the displacement of these electrons.
Electricity manifests itself naturally in many phenomena such as:
The nervous impulses of certain living organisms which emit electric shocks (as for eels);
Static electricity created by rubbing or contacting different materials, for example between hair and wool by removing a sweater;
The lightning which corresponds to an electric discharge between a cloud and the Earth, or between two clouds.
It can also be created artificially in power plants by transforming energy sources:
Fossils such as coal, oil or natural gas, resulting from decomposition in the rock of plants for millions of years;
Fissile materials such as uranium whose atoms can be broken to release heat and energy;
Renewable as water, wind, sun, heat of the Earth or biomass that nature constantly renews.
