Questions tagged [dielectric]
This tag is for questions relating to a non-conducting material called dielectric (or dielectric material). Dielectrics are very much important to explain various phenomena in various fields of physics like solid-state physics, optics, electronics, cell biophysics, etc.
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Force on a dielectric medium
Under the influence of an external electric field the dipoles in a dielectric medium arrange themselves. These dipoles will create a field that opposes the external field, resulting in a net field ...
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Effects on net Electric Potential with the insertion of a dielectric into a network of two capacitors in series?
Suppose you have a circuit with two capacitors of equal capacitance C, C1 and C2 that remain connected to a battery at all times. A dielectric is then fully inserted between the plates of C1. What, if ...
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Confused about the existence of converse effect of Electrostriction
In the research paper (Alan Luna et al., Giant Electrostriction Response and Piezoresistivity of Emulsion Templated Nanocomposites, 2017), the authors mentioned that there is no converse of ...
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Calculating stress tensor from the principle stresses
In the research paper "I. Krakovský et al., A few remarks on the electrostriction of elastomers, 1999" the authors stated the equations of the principle stresses that are produced in an ...
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Do the molecules inside a dielectric physically move when the dielectric is polarized by an external electric field?
Today a colleague and I had a heated debate over whether, when an external electric field is applied across a dielectric, the molecules in the dielectric actually move/rotate (flip to align with the ...
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Why does the relative permittivity of Sapphire not match the square of its refractive index?
According to the Wikipedia, the refractive index of sapphire is around $n = 1.8$ while its relative permittivity $\varepsilon_{\mathrm r}$ is between $9$ and $11$ (depending on the direction). Given ...
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Why do electric field lines bend towards the normal of a linear homogeneous dielectric sphere?
Why do the field lines of the uniform external field bend towards the normal of the linear homogeneous dielectric sphere as shown in the diagram?
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What happens to the capacitance of a capacitor if we didn't allow a dielectric medium to touch the plates?
Usually we will encounter the condition that the dielectric touches both size of the metal plate and this will result in an increase of capacitance in the circuit just by timing the original ...
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Is the electric field between plates of a capacitor change with Polarization charge
We have a capacitor which has a dielectric between the plates in a constant voltage so it ha an electric field $$E_o$$ .
After hours we disconnect the battery so the new field between the plates will ...
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What happens to the electric field of dipoles and in the electric field of capacitors when we introduce a dielectric in a capacitor?
I am trying to understand the concept of dielectric materials.
I know that when we insert a dielectric inside of a capacitor with constant voltage the electric field of the capacitor does not change ...
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Onsager's model to investigate the dielectric constants of a pure polar liquid or a solution
I'm trying to understand the article 'Onsager, Lars. Electric moments of molecules in liquids. Journal of the American Chemical Society, 1936, 58: 1486-1493' in which the author wants to investigate ...
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In Maxwell's equations concerning dielectric materials , does the electric field represent the external electric field or the net electric field?
Let's assume we have dielectric material and we apply an external electric field that acts on it (let's call it Ex ) . As a resault we get dipoles who in turn create another electric field (let's call ...
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Permittivity of free space [closed]
Free space is a region in which there is no matter and no electromagnetic or gravitational field. Which means that the resistance in free space is zero, because there is no resisting force and as far ...
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Maxwell stress tensor for two interacting electric double layers
Imagine two charged and parallel walls in an electrolyte solution:
,
with Equipotential lines as $\psi$ and electric field of $E$.
according to the Maxwell stress tensor, the stress at any point can ...
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Potential Field in space of a "thick" dieletric spherical shell affected by an uniform electric field [closed]
The spherical linear homogeneous dielectric shell has an inner radius $a$ and an outer radius $b$ and is under the influence of an uniform electric field, then what is the potential across all its ...
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Relationship between polarization $P$ and displacement field $D$?
In a paper https://journals.aps.org/prb/abstract/10.1103/PhysRevB.96.235420, there are following derivation of the relationship. For the free energy, there's an electrostatic energy part, the term is $...
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Dielectric tensor in the RPA
The dielectric function in the random phase approximation (RPA) is written as
$\epsilon^{RPA}(\mathbf{q},\omega)= 1 + v_c(q) \Pi(\mathbf{q},\omega)$,
where $v_c(q)$ is the Fourier-transformed Coulomb ...
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Equivalent mass enhanced inside dielectric (modified Rohrlich)?
I shall modify an argument for energy-mass equivalence due to Fritz Rohrlich to be valid inside a dielectric medium with refractive index $n$ and light velocity $c_n=c/n$. (Alternative argument to the ...
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Dielectric (and non-dielectric) Electrostatic Energy - some possible misconceptions and interpretations
Suppose one is given with a system of charges, and is tasked to find the work it takes to build it, in a purely electrostatic situation. Microscopically, it is clear the answer is simply:
$$\iiint \...
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Force on plates of a capacitor, connected to battery,with inserted dielectric slab
Referring to this question, I had a confusion regarding the electric field strength between the capacitor plates. Since we have a constant potential difference across the plates and a constant ...
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Point charge between two infinite dielectrics [closed]
Two infinite linear homogeneous and isotropic dielectrics $\epsilon_1$ , $\epsilon_2$, occupy the regions $z>0$ , $z<0$ respectively. A point charge q is located at the origin. By applying the ...
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Equivalent mass enhanced inside dielectric medium?
Imagine a box of mass $M$ and length $L$ containing a medium with refractive index $n$.
A photon is emitted from the left-hand side of the box and is absorbed on the right-hand side.
Let us assume ...
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How do I calculate the field from a polarised dielectric if there is also a boundary condition?
If we have a polarised dielectric in a vacuum, we can calculate the resulting scalar potential field at a position $\textbf{r}$
$$\phi(\textbf{r})=\frac{1}{4\pi\epsilon_{0}}\int_{\alpha}\frac{\textbf{...
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What is breakdown voltage?
In my introductory text (Resnick and Halliday, page number 732), it is written that
Another effect of the introduction of a dielectric is to limit the potential difference that can be applied between ...
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A Question about AC Conductivity and Optical Properties
I am studying Omar's solid state physics and have reached the optical part.
Here is a equation that I do not truly understand:
In it seems that at low frequency the real part of the dielectric ...
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Salty water impedance vs. frequency
I was experimenting with measuring the dielectric constant of tap-water and also water with salt added.
The measurement was done by submerging a simple cylinder capacitor into a container with the ...
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Energy stored in a capacitor filled with dielectric
while calculating the energy stored in a capacitor of capacitance C to charge up to a voltage $V_{0}$ we say that the work done is move a infinitesimally small amount of charge $dQ$ from the negative ...
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Doubt regarding a theorem in electrostatics of ponderable media
Suppose I have a bunch of charge distribution that is initially there, $\rho_{f}$ denoting the free charge. The field created by this charge distribution is $E_{0}$, and let's say I have two ...
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Dielectric tensor for a lossy medium
Most books and papers tell that the dielectric permittivity (and the magnetic permeability as well) tensor must have Hermitian symmetry (when phasor notation is used, not purely real time functions). ...
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Applying Gauss law between 2 mediums
Consider a closed Gaussian surface crossing the boundary of two different dielectric medium (assume that in a particular medium there's same relative permitivity everywhere) and also consider some ...
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Why do the dielectric caps of parabolic antennas have a metal frame inside?
Why are the so-called radio-transparent dielectric caps covering parabolic antennas based on a metal frame, which, in theory, will work like a Faraday grid, and if it does not absorb the entire signal,...
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Rate of corona discharge
In a corona discharge, the air around a conductor locally breaks down but remains an insulator further away from the conductor. Therefore, in the case of a positively charged conductor, the free ...
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Why is the Lorentz field larger than the external field in isotropic, linear and homogeneous dielectrics?
The definition of the Lorentz field is to apply an external electric field $\mathbf{E}$ on the isotropic, linear and uniform dielectric. At this time, a vacuum ball is assumed inside the dielectric, ...
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Einstein Box in context of Abraham-Minkowski debate
A photon enters a box covered with anti-reflective coatings with total mass M, length L and refractive index n. My question concerns the application of the energy-momentum formula before the photon ...
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Why in an isotropic, linear and homogeneous dielectric, the average electric moment can be expanded as a series of electric field $\mathbf{E}$? [duplicate]
As I was reading this classic 1939 document by Kirkwood The Dielectric Polarization of Polar Liquids. It is stated in the text that the average electric moment in an isotropic liquid can be expanded ...
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How can I calculate this equation if we know that there is non zero Berry-phase between the valence and conduction band
The geometric phase can be interpreted as a Berry curvature in the momentum space. My guess is $(q^2+\text{Berry-phase}/\text{lattice constant}^2)/\text{direct gap}$.
$$\langle\psi_{n',\mathbf{k}+\...
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Where did this extra energy in the capacitor come from?
A parallel-plate capacitor with plate area $A$, separation $d$ and dielectric with $\epsilon = 2\epsilon_0$ is charged up to a voltage $V_0$.
Therefore:
the capacitance is $C_0=2\epsilon_0\frac{A}{d}$...
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Are barium titanate ($\rm BaTiO_3$), magnesium titanium oxide ($\rm MgTiO_3$) transparent to near-infrared rays?
Barium titanate (BaTiO3) and magnesium titanium oxide (MgTiO3) are commonly used dielectric materials in MLCCs. Are barium titanate (BaTiO3), magnesium titanium oxide (MgTiO3) transparent to near-...
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Does Gauss's law (Maxwell 1st eq) have to change when the conductivity of the material is non-zero?
Studying Lorentz-Drude model on any book (e.g. Optical proerties of solids by Wooten, Fisica II by Mencucini-Silvestrini et c.) one finds the following equation relating the relative dielectric ...
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Why do $\omega$, $k$, and electric susceptibility $\chi$ obey this relationship, assuming a dilute-gas?
In the course of writing an undergraduate-level term paper, I'm reading this paper, which provides a simple derivation of the Becquerel relation ($\theta = \nu BL$, describing the Faraday effect) by ...
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Issue in justifying the use of dipole potential in the calculation of bound charges in a dielectric
We have a polarised material, suppose. The goal, is to find the bound charges.
DJ Griffiths (4th ed, section 2.1, page 173) "chops" the material into smaller infinitesimal chunks and writes:
...
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Conundrum due to space averaging electric field inside a charge distribution while calculating the macroscopic Electric field
Given a charge distribution, we are generally interested in the macroscopic electric fields by which we mean the space averaged microscopic fields over a region around the point whose dimensions are ...
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Why does the real part of permittivity (according to lorentz model) converge to 1 faster in materials with less plasma frequency?
according to Lorentz oscillator model that describes optical responses of materials we get a complex permittivity which its real part is given by
we can see that the real part converges to 1 at high ...
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Method of exciting a special mode in dielectric resonator
A dielctric resonator was constructed in a sandwitch like structure.
The middle layer is saphire er=11.5 ,the top and bottom layers are diamond with er=5.68.
A special mode was excited artifficially ...
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Dielectric tensor and electron energy loss spectroscopy (EELS)
Electron energy loss spectroscopy (EELS) is related to the imaginary part of the inverse dielectric function $−𝐼𝑚(𝜀^{−1}(𝑞,𝜔)).$
If the dielectric function $\epsilon(q, \omega)$ is actually a ...
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Electric field and current in a region with dielectric and conductor with current
I am interested in a way to determine electric field and current in a region where some kind of conducting wire is placed in dielectric with some voltage applied to both of them. I am interested in ...
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I'm struggling with a collisionless plasma textbook problem. Calculating the longitudinal dielectric function from the distribution
The problem is:
Given the distribution of the electrons
$$
f_0(\mathbf{p}) = \frac{1}{\pi^2}\frac{mun_e}{(p^2 + m^2u^2)^2}
$$
find longitudinal dielectric function and the dispersion equation for ...
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Can charges shield electric force of attraction?
As given in the picture, the scene is magnified billions of times. Now I am ignoring the force of attractions between q2,q6,q3,q7. Will there be force of attractions between q1 and q2? And suppose the ...
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Quantity that are related to Electrostatic force
Why does electrostatic force depend on medium as in the formula of electrostatic force the $k$ constant is inversely proportional to permittivity and permittivity changes from medium to medium?
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What if we used massive voltages to create a Lichtenberg figure in acrylic?
https://en.wikipedia.org/wiki/Lichtenberg_figure
I cannot find anywhere online what the result would be if I used, for example, 1GeV compared to the 10-20MeV which are usually used. This is all ...
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