Electric Field in the matter - D the displacement field

In summary, the conversation is discussing the concept of displacement field and Gauss Law in relation to finding the electric field produced by a uniformly polarized sphere. The person has attempted to solve the problem in two different ways, but has gotten two different answers. There is a question about whether there should be restrictions on the displacement field.
  • #1
pbp
1
0
Hi,

I try to understand the concept of the displacement field and the Gauss Law for it (the total flux equals to Q free )
1. Homework Statement
for example I try to find the electric field produced by a uniformly polarized sphere of radius.

3. The Attempt at a Solution
I try to solve this problem in two ways:
the first one is to calculate the bounded charge (equals to Pcos(teta)) and from this to calculate the potential and hence the field.
My second approach (whic probably mistaken approach) is to do the following: Since we know that the D=epsilon_0 * E +P and also according to Gauss law we know that the flux thorugh a Gaussian surface equals to the Q_free_in I built a gaussian surface inside the sphere, the total charge equals to zero and therefore I conclude that D equals to zero(the field inside the sphere is uniform) . If so, I can conclude that E= -p / (epsilon_0).

In each way I got 2 different answers...
where is the problem ?
 
Physics news on Phys.org
  • #2
You seem to be saying that for a concentric spherical Gaussian surface [itex]\mathcal{S}[/itex] of radius [itex]r[/itex], you would get:

[tex]\int_{\mathcal{S}} \vec{D}\cdot\vec{da}=4\pi r^2 |\vec{D}|[/tex]

...is that really true?...Don't there have to be a couple of restrictions (symmetries) on [itex]\vec{D}[/itex]? :wink:
 

What is an electric field in matter?

An electric field in matter is a force field that surrounds charged particles in a material. It describes the force that a charged particle would experience at any given point in the material. It is also known as the displacement field or D field.

How is the electric field in matter different from the electric field in a vacuum?

The electric field in matter is influenced by the presence of other charged particles and the material's properties, such as its permittivity and conductivity. In a vacuum, the electric field is solely determined by the charges present and is not affected by the material's properties.

What is the relationship between the electric field in matter and the displacement field?

The displacement field, D, is directly proportional to the electric field in matter, E, and the material's permittivity, ε. This relationship is described by the equation D = εE. The displacement field represents the electric flux density, or the amount of electric flux passing through a unit area.

How is the electric field in matter measured?

The electric field in matter can be measured using a device called an electric field meter. This device uses probes to detect the electric field at a specific location in the material. The units of measurement for the electric field are volts per meter (V/m).

What are some real-world applications of the electric field in matter?

The electric field in matter plays a crucial role in many technological devices, such as capacitors, diodes, and transistors. It is also essential in understanding the behavior of materials in electric fields, including dielectric breakdown and electrical conductivity. Additionally, the electric field in matter is crucial in the study of electromagnetism and electromagnetic radiation.

Similar threads

  • Advanced Physics Homework Help
Replies
4
Views
2K
  • Advanced Physics Homework Help
Replies
7
Views
1K
  • Advanced Physics Homework Help
Replies
4
Views
3K
  • Advanced Physics Homework Help
Replies
26
Views
4K
  • Advanced Physics Homework Help
Replies
2
Views
1K
Replies
1
Views
908
  • Introductory Physics Homework Help
Replies
17
Views
327
  • Advanced Physics Homework Help
Replies
17
Views
1K
  • Introductory Physics Homework Help
Replies
12
Views
984
  • Advanced Physics Homework Help
Replies
7
Views
4K
Back
Top