In electricity, there are two types of electrical charges: positive and negative. Main positive particles are protons, while the main negative charges are electrons.
The behavior of these charges are determined by the following laws:
- conservation of electric charge: the net charge of isolated system remains constant;
- Coulomb's law, which determines the interaction between the charges: like charges repel, while unlike charges attract.
If a solid (or any other material) is neutral then there are equal number of positive and negative charges. In relation to distribution of the charges inside the solids (and in relation to response of the solids to external electric field), the solids can be devided into two main classes:
- conductors and
Conductors: the positive charges inside conductor are at fixed periodic positions - they form crystal lattice. The negative charges (electrons) can move freely through the whole volume of the solid - the system of such negative charges is called electron gas.
Insulators: positve and negative charges are at fixed positions. Negative charges (electrons) are near positive charges - they form dipoles. There are no free negative charges.
Below you will find animations of different concepts related to electricity.