Presumably, you know the experiment from school, as you can create electricity by rubbing a rod made of plastic on a cloth charge. This means that our knowledge of the nature of electricity is much older than its use. The term thus comes from the Greek and is the translation of 'amber', where probably the first phenomena have been found.

The time around 1800 brought the connection of charge by friction to magnetism. The first battery by Volta 1799 was able to store electricity electrochemically and allowed it to flow fairly smoothly. The Danish physicist Hans Christian Ørsted was the first to visualize the magnetic effect of current flowing in a wire and its effect on a compass needle.

For a current to flow, there must be one positive and one negative pole each. This distinction was already known before, because rubbing an amber or glass rod with silk, charges arise that cause such treated silk towels and glass rods repel each other, of course, attract silk cloth and glass rod.

Thus, the imaginary surplus and the lack of charges, the plus and the minus arise. Only later did they discover the carrier of the charge, the electron. And since they had already set the supposed surplus of charge as a plus side, they now had to assign the carrier to the negative side. Since then, the imaginary surplus of charges has to be looked for in the form of electrons on the minus side.

The electron sets the smallest possible unit for the charge. If it could be isolated ether, it would be in the extremely airy envelope of each atom, as many of them as protons with positive charge in the comparatively tiny but massive nucleus. As already indicated, it occurs as matter and/or as wave.

As matter understood, one can assign a mass to the electron, which is then about 2000 times smaller than that of a proton. Nevertheless, the charges are always consistent. The process referred to as "charging" creates, in principle, an altered distribution of charges, which is compensated for by the 'consumption' of electrical energy. So the electric charge remains constant overall.

Electricity is generated by moving charge. There are materials in which this comparatively well, such as metals, and those that do not allow charge movements, such as porcelain. The former are called conductors or insulators, the latter non-conductors. Basically, the conductivity varies depending on the material. Gold. Silver and copper are considered very good conductors.

To conduct electricity so-called 'free' electrons are needed. Whenever a particular model of the atom is used, in this case, that of Niels Bohr. The more they are and the farther they are away from the atomic nucleus with the inverted, positive charge, the freer, that is, the more mobile they are. If you separate the electron from its nucleus during 'loading', the atom becomes more positive overall.

Thus, when charging a battery, a positive pole with electron deficiency and a negative with excess of electrons. Connecting both poles without an additional electrical consumer or a resistor creates a short circuit. Depending on the number of excess of electrons, a large current flows, which can cause the connecting wire to glow.

Such processes are almost always associated with heat and can damage the battery sustainably. For the course of the chemical processes there takes a certain amount of time. Around the line, a circular magnetic field forms, even at a lower current flow, whose direction depends on the polarity of the line. If you turn them over, a compass needle positioned at an imaginary tangent to a circle around the wire also turns over.

This attraction force acting in a circle represented by the compass needle can be visualized by one of several force or field lines. Besides the direction, there is also a magnitude of the force with which the needle was torn around. You may still know the two-dimensional visualization of field lines with the help of iron filings. Field lines form from the positive side to the negative, the stronger the field, the denser the lines.

Electric fields play a role each time something is to be transmitted purely electrically without a line connection, excluding radio links this time. This is e.g. the case with the old CRT television, where electrons are generated on the opposite side of the screen from where they are directed distractedly onto it, so fast that our eyes perceive the resulting dots as a complete picture.

We mainly need electric fields when operating electric motors without brushes and with inductive charging. Especially with the former, the force exerted by a package of lines hardly enough. It has to be reinforced by special materials. In order to be able to describe better the required material properties, we should, for example, to metal to be magnetized envision as composed of smallest single magnets.

Physics describes this as a 'system of two oppositely equal point charges' *, also called dipoles. So if we want to use a common screwdriver to take a screw out of a sinkhole, where perhaps an existing magnetic rod with a rectangular cross section can not get it, then it is sufficient to let the bar magnet slowly slide over the metallic part of the screwdriver in one direction and it will become magnetic.

Magnetism arises when arranging the dipoles in a material. But now there are materials that are a bit simpler than others. In electric engines, those are required which are particularly fast. The shape of the material to be magnetized also plays a role. You may have heard of or dismantled so-called 'transformer sheets'. These are sheets of soft iron that, when placed on top of each other, allow for a fairly flexible alignment of dipoles.

*Physik, ISBN978-3-642-54165-0, S. 675