Does the Net Charge of a Dielectric Affect the External Electric Field?

In summary, the conversation discusses a scenario involving a sphere with uniform volume charge density and a dielectric coating. The total bound surface charge on the dielectric is zero, but there is a non-zero volume bound charge. The effect of this charge on the electric field outside the dielectric is debated, with one argument stating that it has no effect due to the free charge on the sphere, and another arguing that the effect can be determined using a Legendre polynomial expansion. It is suggested that the external field will be non-zero due to the monopolar and dipolar sources from the central sphere and the coating, respectively. However, further analysis is needed to confirm this.
  • #1
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Let's say we have a sphere, radius R, which has a uniform volume charge density. Then we wrap it around with a dielectric with a frozen in polarizability of kz in the z direction. This dielectric goes from R to a radius A. The total surface bound charge on either surface of the dielectric is zero; however, the volume bound charge total is -4/3(A^3-R^3)*pi*k. Now I would think that this net charge would change the E field outside the dielectric. Looking at it through the electric displacement vector shows that in a region outside the dielectric, the E field would be determined only by the free charge on the sphere. Which would say that the charge of the dielectric has no effect. Anybody who would know which of these scenarios is actually happening and why?
 
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  • #2
Although the total bound surface charge (bsc) is zero, the bsc varies with angle.
Therefor, you cannot use Gauss's law.
The problem requires a Legendre polynomial expansion.
 
  • #3
The external field will be non-zero, because the central sphere is a monopolar source and the coating is essentially a dipolar source.

As a first attempt at the answer I would add the fields from: monopole sphere (radius R) + dipole sphere (radius A) - dipole sphere (radius R)

I would guess given the geometry that this is actually correct but this would need to be proven properly.
 

What is a dielectric with net charge?

A dielectric with net charge refers to a material or substance that has a non-zero amount of electric charge distributed throughout its volume.

How does a dielectric with net charge affect electric fields?

A dielectric with net charge can either enhance or reduce the strength of an external electric field, depending on the direction of the net charge and the polarity of the field.

What is the difference between a polar and non-polar dielectric with net charge?

A polar dielectric with net charge has a separation of positive and negative charges within the material, while a non-polar dielectric has no separation of charges.

Can a dielectric with net charge store electric energy?

Yes, a dielectric with net charge can store electric energy in the form of potential energy within its electric field.

How does temperature affect the net charge of a dielectric material?

In most cases, an increase in temperature leads to a decrease in the net charge of a dielectric material due to increased thermal motion and the ability of charges to move more freely.

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