Translations of Encyclopedia about Physics

An atom becomes charged when the number of electrons within it change. An atom is made up of electrically charged ions and an electron has the smallest, indivisible charge, called the elementary charge. Every other charge should be considered as a multiple of the elementary charge.

There is always an electrostatic field associated with an electrical charge.

If the object containing the electrical charge is moved into close proximity with another object, the charge within its molecules is either repelled away from or attracted to the other object, depending on whether they have current or nonconcurrent (same or opposite) charges.

The movement of an electrical charge is called an electric current and is measured in amperes (A). Electrical current travels from a negative field to a positive one (from the minus sign to the plus sign). This technical direction of the current’s movement is, uncannily, defined as the opposite direction.

Negatively charged electrons can move through conductive materials, where there is a loose connection between the electrons. If a charge is flowing through the conductor, we refer to it as a conduction current, as opposed to for example an eddy current, which is induced in some object.

Conductive materials have loose electrons which enable the flow of a current. The higher the conductive ability of the material, the greater the number of loose electrons it has.

From an electrical point of view, we make a differentiation between conductors, semiconductors and non-conductors. Metallic materials are best for currents. Electrical conductivity also depends on the chemical composition of a substance. Water is also considered a conductor and air becomes a conductor only between two, closely lying highly charged fields, when a so-called discharge of gases takes place (spark, etc.).

A distinction is also made between direct and alternating current. With direct current, electrons move or flow in only one direction where, with alternating current, the direction of the current constantly changes. According to some more detailed definitions of direct current, its magnitude also remains constant.

The magnitude of forces which induced the flow of electrons is referred to as voltage and is measured in volts (V).

Contact electricity also takes place with many materials. Contact electricity is an electrical effect which occurs when certain materials come into contact with one another. Such materials have differing concentrations and movements of charge carriers and, when their surfaces come into contact with one another, there is a transfer of electrical charges, which essentially results in one of the objects charging the other, creating an electrical charge between both of them.

This process can explain to us the creation of electricity caused by the friction of certain materials rubbed against one another.

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