Equipotential surface

An equipotential surface, also equipotential surface or surface potential, is the set of all points of the same (Latin: aequalis ) potential, that is the same potential energy of a test specimen in a potential field. This surface is always perpendicular to the field lines and is a special case of iso-surfaces.

The profile of the potential field in 2D is often depicted with the help of equipotential contours.

Electric potential

Here it is a surface whose points all have the same electric potential. Thus, the voltage U between two points of an equipotential surface is zero. Work to be performed, the electrical work, for moving a carrier from a point to another point of the equipotential surface of the same equipotential surface is also zero.

Ideal conductors are in static fields exactly ( at sufficiently low frequencies: almost) equipotential surfaces, as each potential difference would rapidly compensated due to the infinitely high conductivity. For metals (very high but finite conductivity) are the electric charges are also free to move. Only if they are not subjected to force, ie no field strength, they are in equilibrium. They follow a field occurring very rapidly until the field is compensated. It follows that (apart from those usually short-term imbalance states) the potential has the same value everywhere ( inside and on the surface of a conductor ). For a detailed discussion see Faraday cage.

Gravity potential

Here the equipotential surface (also Geopotentialfläche level surface on the earth ) is a surface whose points all have and its gradient ( spatial variation ) is called the acceleration due to gravity the same (effective) gravity potential. On an equipotential surface of the gravity is the gravitational acceleration, which is composed of the gravitational acceleration and the centrifugal acceleration, the same everywhere. In a rotating celestial bodies, the equipotential surfaces of the gravity therefore usually do not run parallel to the surface. At the poles of the celestial body about the effective gravitational acceleration is greater than at its equator, so the equipotential surfaces are also higher at the equator than at a point at the pole. However, density differences inside the celestial bodies lead to deformations of its gravity field.

The geoid is the equipotential surface of the gravity field of the earth at the level of mean sea level, ie all points that have the same geopotential, composed of the gravitational potential and the centrifugal potential at that location. Orthometric heights using these Geopotentialflächen for height definition.

Surface tension

Due to surface tension liquids form equipotential surfaces ( ideal under microgravity ).