# Questions about the electric field in an air/ionic media interface

• Sancor
In summary, in the system described with an electric field applied by a capacitor over two media, the vertical electric field in the ionic media is zero due to the conservation of charge and Ohm's law. This is because any electric field in a conductor would lead to a current, which would then reduce the electric field. Additionally, this system is known as a "double layer capacitor" and there is no field inside the electrolyte due to it being a conductor, but there is a strong field in the double layer.
Sancor
Hi there. I'm trying to consider a system in which you have an electric field applied by a capacitor over two media, namely an air gap and then a solution containing a bivalent ionic concentration.

++++++++
air
-------------
ionic media
-------------

If a DC potential is applied between the top and bottom electrodes, you should be able to consider the electric field using the boundary condition supplied by conservation of charge:

Layer 1 (Dielectric, air, conductivity = s1 = 0) : Layer 2 (conductivity = s2)
Jn1=Jn2 Current density continuation equation (n is the normal component)
E1n*s1=E2n*s2 Ohms law
0=E2n*s2 Since Jn1=0
E2n=0 Since s2 =/= 0

This implies that the vertical electric field in the ionic media must be zero. I'm having a hard time believing this. Could someone offer some physical reasoning as to why this is?

Last edited:
An electric field in a conductor would lead to a current - and that current reduces the electric field. In equilibrium, you don't have a current and therefore you don't have an electric field.
That is equivalent to your equations, just with words.

A capacitor with an ionic media (aka electrolyte) and without an insulating layer is called a "double layer capacitor"
http://en.wikipedia.org/wiki/Double-layer_capacitor
There is no field inside the electrolyte since it's a conductor. There is however a strong field in the double layer.

## What is an electric field?

An electric field is a physical phenomenon that is created by the presence of electrically charged particles. It is a force field that surrounds the charged particles and exerts a force on other charged particles within its reach.

## How is an electric field measured?

Electric fields are measured in units of volts per meter (V/m). This unit represents the strength of the electric field at a certain distance from a charged particle.

## What is the difference between an air and ionic media interface?

An air media interface refers to the boundary between air and another material, while an ionic media interface refers to the boundary between two materials that have a difference in their ionic charges. The behavior of electric fields at these interfaces can vary due to the presence of charged particles in the ionic media.

## How does an electric field interact with an air/ionic media interface?

An electric field can cause charged particles in the air/ionic media interface to move and rearrange, leading to changes in the overall strength and direction of the field. The behavior of the electric field at the interface can also affect the movement of charged particles in the surrounding media.

## What are some applications of understanding electric fields in air/ionic media interfaces?

Understanding electric fields in these interfaces is important for many practical applications, such as in electrostatic air filters, electrostatic precipitation, and electrostatic painting. It is also important in the study of atmospheric electricity and the behavior of lightning.

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