Can a rotating dielectric disc be polarized?

In summary, rotating a dielectric disc does not always result in polarization. However, if the dielectric has been previously polarized, the rotation may cause the polarization to be destroyed.
  • #1
sergiokapone
302
17
Can a rotating dielectric disc be polarized? No external electric or magnetic field .
 
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  • #2
Of course it can. If it was previously polarized, the rotation will not necessarily destroy the polarization.
But I suspect this is not what you mean to ask. Do you mean if the disk can become polarized due to rotation?
 
  • #3
nasu said:
Do you mean if the disk can become polarized due to rotation?

Yes, I do.
 
  • #6
How do you think that polarization of a dielectric happens in presence of an electric field?
 
  • #7
I think polarisation should be appear due to electric field, which is created by
reclined free light weight charges (electrons), due to the centrifugal force. But if we have ideal dielecrtic, where we can get this FREE charges?

Or another way. Polarisation can happen due to mechanical deformation of the piezoelectric, but this is not the case.
 
Last edited:
  • #8
A dielectric has no free charges. Still can be polarized in electric fields.
You don't need free charges to have polarization.
 
  • #9
nasu said:
Still can be polarized in electric fields.
You don't need free charges to have polarization.

Of course, but where I get this field? Assumption of the problem - is no electric field, only a rotation disk.
 
  • #10
Yeah, but do you understand that you don't need free charge?
You said that you don't understand the paper and one of the reasons is that there is not free charge in dielectric.
The paper says right in the beginning that accelerated motion of the dielectric can result in polarization. You may find it easier to think about it in terms of inertial forces, in the accelerated frame. The inertial forces will be different for the light electrons than for the heavy nuclei so it may result in a slight displacement of the centers of mass of the two types of charges. This is polarization.
 
  • #11
Now I see. Thank you. How can I calculate polarisation depend on rotational frequency?
 
  • #12
I think centrifugal force - is the some kind of electric field:
##m\omega^2 r = eE##
Then polarisation is equal to ##P = \frac{\epsilon - 1}{4\pi} \frac{m}{e}\omega^2 r##

So, I can also find charge density as ##\rho = -div \vec P##
 
  • #13
I think you should take the difference in force between electron and nucleus but in first approximation it may be OK.
The problem is that the force is not uniform and so neither is polarization.
But again, the change in r will be small at the level of few atomic distances.
 

1. Can a rotating dielectric disc be polarized?

Yes, a rotating dielectric disc can be polarized. Polarization is a process by which the electric field of a wave is confined to a single plane. This can be achieved by applying an external electric field to the dielectric disc, which causes the molecules within the disc to align in a specific direction, resulting in polarization.

2. How does polarization affect a rotating dielectric disc?

Polarization affects a rotating dielectric disc by altering the behavior of the electric field within the disc. When the disc is polarized, the electric field is confined to a single plane, causing the disc to rotate in a specific direction. This can also result in changes in the disc's optical properties, such as light transmission and reflection.

3. What are the applications of polarized rotating dielectric discs?

Polarized rotating dielectric discs have a wide range of applications in various fields, including optics, telecommunications, and electronics. They are commonly used in devices such as polarizers, waveplates, and optical filters. They are also used in radar systems, satellite communication systems, and LCD displays.

4. Can the polarization of a rotating dielectric disc be controlled?

Yes, the polarization of a rotating dielectric disc can be controlled. By adjusting the strength and direction of the external electric field applied to the disc, the degree and direction of polarization can be changed. This allows for precise control of the disc's rotation and optical properties.

5. Are there any limitations to polarizing a rotating dielectric disc?

Yes, there are some limitations to polarizing a rotating dielectric disc. The effectiveness of polarization depends on the material of the disc and the strength of the external electric field. Some materials may not polarize easily, and high voltages may be required to achieve polarization, which can be impractical. Additionally, the polarization may not be stable over time and may require constant adjustments.

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