Permittivity Definition and 143 Threads

Greetings. I don't know how to use an equation with a complex frequency term, specifically this one (aka Debye expression) for frequency-dependent permittivity: epsilon(omega) = epsiloninfinity + delta-epsilon/(1 + j*omega*tau) where epsilon(omega) is the permittivity at omega angular...

I read that in some ferroelectrics,such as Barium Titanate, dielectric permittivity approaches infinity near Curie point. For example,for Barium Titanate it`s closer to 120 centigrads. Do those effect allow as (in theory) create capacitor with almost unlimited energy density?Or there are...

What does negative electric permittivity mean?

Hi, I am trying to drive this famous equation: ε_r(ω) = 1 + iσ(ω)/(ε_0*ω) First the regular solution: J=∂P/∂t→In Fourier domain→J=iωP(ω)=iω{D(ω)-ε_0*E(ω)}; then replace J with σ(ω)*E(ω) and rearrange to reach the result What makes me puzzle is we know that J_external is equal to...

I read from a paper that we can generate the permittivity variation by low-frequency electro-optic modulation. So, does anyone know, how this modulation changes the permittvity? or a link will be appreciated!

Hi, It is seen that noble metals (gold, silver) show a negative permittivity in optical frequencies. Can somebody explain the physical interpretation of this phenomena? How is the negative permittivity measured? Really appreciate if someone could point me in the correct direction. Thanks.

Homework Statement in a homework problem we have a spherical dielectric shell with permittivity of 1 [like a vacuum. inside are charges that are released and we have to say what the charge distribution will look like later. if the dielectric can be polarized, i know what the charges will do...

Does anyone know how quantum theory accounts for a ε value that is negative? Wouldn't this change probability densities?

I've been told recently that the vacuum permittivity, given a sufficiently strong electric field, is not a constant, as it can cause positron-electron pair to split out of the vacuum. 1) is this true? 2) if so, where do such pairs as the positron-electron come from in a vacuum? I did try to...

Homework Statement Is the relative permittivity (ie.dielectric constant) of a conductor (metal) zero,or,infinity? Prof. Jaiswal in his golden physics (for XII std. CBSE) states that it is "zero". Another author Prof. Mohindroo in his book based on the same XII std. CBSE physics syllabus...

Statement: Permittivity ε = ε_{r}ε_{0}. I understand the definitions of each permitivity, where the former is the relative permittivity (of the dielectric), and the latter is of the free space between the plates of the capacitor. But can someone explain to me, why they are multiplied and not...

Background reading from Wikipedia I read the following from Wikipedia, Question How does a dielectric's dipole becoming polarized

funny but I could not reach the info from net quickly.

What is the relative permittivity of gold at radio-frequencies or specifically around 15-20MHz?

Electrical permittivity...in mathematical terms, i.e I need the derivation...WITHOUT using 'curls'. Didn't find it online.

Hi, Can u point out physical interpretation of the complex permittivity? (ie. what can u expect from a material with \epsilon' = x and \epsilon'' = y ? what happens if y is very large etc. \epsilon = \epsilon' -j \epsilon'' thanks Krindik

Maxwell showed us that the speed of light in vacuum is dependent on two values. The two values are the electrical permittivity and the magnetic permeability. But how are these two values measured?

We know for sure €0 and µ0 for free space. We know as well €r and µr for material Have theses values been calculated for stand alone particles like an electron, a proton or a neutron? Have somebody then connected theses values to an atom (of hydrogen for example) which is a combination of...

I have an relation between permittivity and conductivity as follows: \epsilon(\omega) = 1 + \frac{4\pi\iota\sigma(\omega)}{\omega} Yet am unclear as to how it was derived. Does this relationship have a name and/or derivation to follow through somewhere? also, I believe it is cgs units...

could anyone offer a decent explanation of how a negative permittivity (dielectric constant) is obtained using the wire-mesh method.. i understand the process with plasmons and metals but this one seems a bit beyond me at the moment <<! any thoughts??:biggrin:

I am wondering how to different dielectric material with different relative permittivity behave when put together. Say i have two concentric sphere and the space between them is filled with a dielectric of relative permittivity A from the outer surface of the inner sphere to the mid point...

I am given the permittivity to be \epsilon(\omega) = 1+ \frac{\omega_p^2}{\omega_0^2 -\omega^2} I am asked to sketch k vs \omega using the dispersion relation k^2 =\frac{\omega^2 \epsilon(\omega)}{c^2} here is what I have: k=\frac{\omega}{c} \sqrt{\epsilon(\omega)} k=\frac{\omega}{c}...

Hey. Is the conductivity of a material related to the dielectric constant (permittivity) in some way? And what about the electrical susceptibility? Thanks

hi..i'm an undergraduate student.i'm working on my final year project. I've been looking for the permittivity and permeability of ErAs, SI or any metamaterial but i find it difficult to get. i hope this forum could help me (n hope this forum is still active..hehe) THANX! o:)

How is permittivity a function of frequency ? And how is permittivity a function of frequency in relation to the refractive index ?

in relating the index of refraction to the relative permittivity (dielectric constant/function). it is known that n = \sqrt{\epsilon_r} for optical frequencies (i.e. \mu_r=1. now this website http://hyperphysics.phy-astr.gsu.edu/Hbase/tables/diel.html#c1 gives the relative permittivity of...

Homework Statement A spherical capacitor (shell radiuses a and b, a<b) has the space between the shells filled with a dielectric, and the permittivity changes as a function of the radius so that the energy density stays constant (when radius R=a, then er=e1). Find the permittivity as a...

I can't seem to demonstrate that in anisotropic materials the permittivity matrix is symmetric, apparently this is done with the poyinting vector... I really need to understand it thanks...

Hey As some of you may have seen i have beeen doing an experiment measuring the permittivity of water in an attempt to calculate the refractive index. This has produced some odd readings as my experiments concentrate in the static range of permittivity i should be seeing a permittivity of...

Hi! Im woundering if the relative permittivity in a capacitor is dependent on the level of charge in the capacitor? /Nikke.

Complex Dielectric Permittivity! Homework Statement Calculate the power dissipated per unit cycle in a dielectric medium per unit volume in terms of the dielectric loss and the strength of the electric field The previous question was: Why does the dielectric permittivity of a material in...

Imagine that one could alter the electrical permittivity or the magnetic permeability of the vacuum. How would this affect for instance the size of an atom or the size/length of a piece of material ?

Hi, recently my class did an experiment to find the relative permittivity of polythene. I did some calculations by comparing the capacitance of 2 metal plates with air between them and the same capacitor with a sheet of polythene. It turned oout to be 1.57. However, I googled and it seemed to be...

Hi, What is a good interpretation of electric permittivity? If you look at Coulomb's law, it seems that the electric field due to a given source charge is inversely proportional to the permittivity of the medium where the charge is located. Furthermore, the electric permittivity of a simple...

Speed of Light c= \frac {1} {\sqrt{\varepsilon_0\mu_0}} Phase Velocity v= \frac {1} {\sqrt{\varepsilon\mu}} Electric Permittivity of Free Space \varepsilon_0 = 10^{7}/4\pi c^2 \quad \mathrm{(in~ A^2\, s^4\, kg^{-1}\, m^{-3}, \, or \, F \, m^{-1})} Magnetic Permeability of Free Space...

Permittivity of a vacuum is a number arrived at beginning with a value for the speed of light in the vacuum and the permeability of the vacuum. NIST uses the term "electric constant" for what is commonly known as the permittivity of free space: Here's their official value...

I'm feeling a bit lazy, but curious. What experimental results confirm the values assigned for permeability and permittivity [as it relates to c]? I haven't explored the literature very thoroughly, but, have not been altogether satisfied with what little I found. Thanks!

I want to know if the orientational polarization should be included when you calculate the permittivity of the silicon oxide (both crystal and amorphous)?

Does anyone know of a physical explanation of \epsilon_{0} and \mu_{0}?

Can anybody please tell me where I can find the value for the relative permittivity of copper with respect to air. Thanks

Meaning of "Permittivity" as used in EM Hello all, I am having difficulty with the concept of permittivity as used in EM contexts. What is it a measure of? What is its physical meaning? One thing that puzzles me is the relationship between electric field and permittivity: E =...

Suppose 2 inertial frames with relative relativistic velocities. To discuss phenomena in other frame, we need to use Lorentz Transform for length and time. I got question: do we have to also use LT to talk about permittivity and permeability of other IRF? This seems strange. Permittivity has...

Could someone please tell me the most detailed and direct definition of permeability and permittivity. I know that they are porportionalities of some sort but what else could they be viewed as? Why is &epsilon;&mu; = 1/c^2 ?