Electric flux

The electrical flow or displacement flow Ψ (Psi ) is a physical quantity from electrostatics and electrodynamics, although has a certain similarity with the flow in a flow field, but nothing material such as charge carrier transported, but only the effect of the underlying force field of a transmits it to another point. The electric flux as physical size, however it also has mathematical properties that resemble those of a real flow.

Representation

The concept of electric flux Ψ is closely linked to the electric field strength and can be depicted in the electrostatic case, for ease of presentation: If you compare the direction of the electric field strength at any point of the room by field lines, which fall away by definition of positive charges to negative and charges point towards, one can represent the amount of the electric charges on the surfaces of the electrodes in that it records the lines of the closer to the conductor surface, the greater the charge density at the location concerned. The number of field lines that extend or end of an electrode total is equal to the electric flux, which originates or terminates at that electrode that electrode. Thus, the outgoing flow from one electrode is equal to the electrical charge of the electrode.

This circumstance can also be expressed by saying that an electric voltage U is transported a predetermined charge to the plates (electrodes ) of the capacitor to a capacitor having the capacitance C. This tension between the capacitor plates causes an electric flux Ψ of size

Thus, the electric charge Q of the capacitor exactly matches with the electrical flow between the electrodes.

Since the electric flux Ψ can not be assigned to individual points in space (sometimes therefore remedy is to gradually in the representation of the river with extensive spatial flux tubes ), any point in space is assigned to an electric flux density D. While taking account of only those electric flux component that is normal to the surface A, the electrical flow through the area A in. In mathematical terms, this circumstance in the vector analysis using vectors and by the operation of the inner product as a surface integral:

Different concept definitions

Depending on the unit or system context used, the electric flux is sometimes defined differently, which can lead to confusion. The above definition is mostly used in the electrical engineering literature, based on the International System of Units. The relations with the matter and the ratio of flows are described to field strengths of the material equations of electrodynamics. However, for example, especially in the physical literature, for example in physics Gerthsen, the electric flux or under vacuum in the form:

Determined. Those Definition of electric flux Φ is different despite the same naming of the above definition of the concept of electric flux Ψ. Thus, the electric flux Φ does not match the surface integral of the electric flux density D, but the electric field strength E. In addition, arise in this setting in matter, especially for nonlinear and anisotropic materials, complex relationships with the electric flux Φ.