Electric field strength
|Electric field strength
The physical quantity of electrical field strength describes the strength and direction of an electrical field , i.e. the ability of this field to exert force on charges . It is a vector and is defined by at a given point
A certain amount and a certain direction of the electric field is assigned to each point in space. In field line pictures , the lines run in the direction of the field at every location, from positive to negative charges; The amount of field strength can be read off from the line density (in the room).
Size concept for the electric field strength
|Electric field strength E
|100 to 200 V / m
|400 V / m
|Dielectric strength of the air
|3 MV / m
|1 to 10 MV / m
Relationship with the electrical flux density
Also used to describe the electric field is the electric flux density , formerly also called displacement density , which is linked to the electric field strength via the material equations . The relationship applies in a vacuum
with the electric field constant .
Connection with the potential
In many cases, the electric field strength can be calculated using the associated potential . In the context of electrostatics, the electric field strength is equal to the negative gradient of the (scalar) electric potential :
The corresponding more general equation of electrodynamics also takes into account the vector potential and the time dependence:
- Adolf J. Schwab: Conceptual world of field theory: practical, clear introduction. Electromagnetic fields, Maxwell's equations, gradient, rotation, divergence . 6th edition. Springer, Berlin 2002, ISBN 3-540-42018-5 .
- See Altmann / Schlayer, 2003, p. 34