# A question about Volume charge density and electrostatic equilibrium

• Lanza52
In summary: It only tells the total charge in a given volume.In summary, the conversation discusses the concept of volume charge density and electrostatic equilibrium. The existence of one seems to render the other pointless, and volume charge density is a theoretical construct that may never exist in practice. However, even materials that are not perfect conductors can still neutralize an electric field within them over time. The question raises the point that volume charge density does not imply an even distribution of charge, but rather the total charge within a given volume.
Lanza52
The concept of volume charge density is an even distribution of charge over a three dimensional area. C/m^3. However, the concept of electrostatic equilibrium says that all of a conductors charge lies on the surface of the conductor.

The existence of one seems, to me at least, to render the other pointless... Anything less then a perfect non-conductor would nearly instantly rearrange the charge towards the surface. So a volume charge density is a purely theoretical construct that will never exist. So any application of it is just in practice to demonstrate the math.

Am I missing something?

Most materials are not perfect conductors.

The question is even it is not a perfect conductor...even a lossy material, as long as electrons can flow, any electric field inside the material will cause the electrons(charges) to flow and neutralize the field.

This is like you put a potential across a high value resistor ( say 10ee12 ohm), the moment you remove the voltage source, the potential across the resistor will immediately goes to zero. The resistor will not maintain the voltage ( field ) across by itself, electrons will stop flowing and no field is left.

For dielectric with very low conductance, it might take longer time for the charge to move to neutralize the internal field, but it will eventually.

This is actually a very good question.
To the OP, volume charge density do not imply even distribution. Charge density can vary from point to point inside.

Last edited:

## 1. What is volume charge density?

Volume charge density is a measure of the amount of electric charge per unit volume in a given region of space. It is denoted by the symbol ρ and is typically measured in units of coulombs per cubic meter (C/m^3).

## 2. How is volume charge density related to electrostatic equilibrium?

In electrostatic equilibrium, the electric field within a conductor must be zero. This means that the volume charge density must also be zero, as any excess charge would create an electric field. Therefore, in order for a system to be in electrostatic equilibrium, the volume charge density must be constant and equal to zero throughout the conductor.

## 3. What factors affect the volume charge density?

The volume charge density can be affected by the presence of other charges in the vicinity, the material of the conductor, and the geometry of the conductor. It is also affected by the dielectric constant of the material, as this determines how much charge can be stored per unit volume.

## 4. How is volume charge density calculated?

Volume charge density is calculated by dividing the total charge by the volume in which it is contained. For example, if a charge of 5 coulombs is contained within a volume of 2 cubic meters, the volume charge density would be 2.5 C/m^3.

## 5. Why is volume charge density important in electrostatics?

Volume charge density is important in electrostatics because it helps us understand the behavior of electric fields and the distribution of charges within a conductor. It is also used in calculations and equations that describe the behavior of charged particles in electric fields. Additionally, volume charge density plays a role in determining the capacitance of a system, which is important in many applications such as electronic circuits.

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