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2
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1answer
25 views

Question about wavelength of EM wave in dielectric

Many websites (http://maxwells-equations.com/materials/permittivity.php) lists out the following formula as to how you can compute the wavelength of an EM wave in a dielectric $$\lambda_d = ...
-2
votes
0answers
20 views

How to write Laplace equation for this problem? [on hold]

How to write Laplace equation in below example. we have two plate with surface S,If we have charge surface density in boundary,obtain potential between two plate. explicitly explain for me how to ...
0
votes
0answers
11 views

Introducing a conductor in a capacitor [closed]

1) A capacitor is taken and a Conductor (Not a dielectric) is inserted in between the plates (made of a different material other than the conductor) like: What will be the new capacitance, How much ...
0
votes
0answers
15 views

Dependence of capacitance on its build material

We know that the capacitance of a capacitor depends on the dielectric material in between the plates as $$C=\dfrac{K\epsilon_0 A}{d}\,.$$ But what if the electrode material is changed? For example ...
1
vote
0answers
15 views

Dielectric constant of gases - constant?

A number of questions related to the topic: Is the dielectric constant actually constant as a function of temperature and frequency (when used in a capacitor)? Is it constant as a function of field ...
0
votes
1answer
18 views

Why does material change electrical property based on frequency of input electrical signal?

I was investigating whether dry soil would conduct electricity. What I found was that at 60 Hz frequency (i.e. power line fell to the ground), dry soil is a very good conductor. But if you increase ...
0
votes
1answer
14 views

How does the dieletric displacement change among two dieletric materials?

Here's a question I am working on. "A sphere of linear dielectric material with permittivity $\epsilon_1$ and radius $a$ is surrounded by an infinite region of linear permittivity $\epsilon_2$. In the ...
0
votes
1answer
36 views

Why does energy rise in a constant voltage capacitor after inserting a dielectric?

For example from this link: http://te.fisica.edu.uy/fuerza_en_Capacitor.pdf we can deduce, that the work the electric field inside a constant-voltage capacitor does during the insertion of a ...
0
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0answers
24 views

Addition of forces in dielectric material

In this paper (page 2 of document) it is said that: Because this calculated force was comparable to the gravitational force, they assumed that the same would be true for the forces on a ...
3
votes
0answers
96 views

Green's function for a dielectric with a charge [closed]

Suppose there are two infinite planes, one in $z=a$ and the other in $z=b$, with $a<b$. Between the planes, there is a dielectric medium with constant $\epsilon_1$. The differential equation for ...
0
votes
0answers
18 views

Complex dielectric constant in ultraviolet range

Dielectric constant of a material could be a complex number, which is dependent of the frequency of electromagnetic wave. From the Springer material website, I learn that both the real part and ...
1
vote
2answers
75 views

What is the speed of an electric spark/arc in vacuum?

I am just curious about the nature of an electric spark, how fast are the electrons moving? Will these electrons slow down when the spark occurs through a dielectric? (e.g., air)
0
votes
0answers
26 views

Determining if an object is dielectric or metallic

In a worksheet I was given, I had to find the net electric field of P which is L distance away from a bar. The last question is ...
0
votes
3answers
107 views

How do we conclude that polarized dielectric in electric field reduces overall field?

If we have a dielectric inside an electric field, the dipoles in the dielectric will align in the following direction due to the torque on them by the external field. The conclusion then is that ...
0
votes
1answer
70 views

Microscopic understanding of Brewster angle

The textbook explanation is that, at Brewster's angle, the electric dipoles excited by the incident light can't reradiate to the reflection direction since it's aligned with the dipole moments. Is ...
3
votes
2answers
119 views

Refractive index of dielectric in different frames of reference

The setup A transparent isotropic dielectric medium moving in the negative $x'$ direction at speed $v$ in frame $S'$ is stationary in frame $S$, where it has refractive index $n$. In other words, ...
2
votes
1answer
98 views

Looking for a simple proof of symmetry of linear susceptibility tensor

Getting a diagonal susceptibility tensor: Define the linear susceptibility tensor as $\chi_{ij}$: $P_i = \epsilon_0\chi_{ij}E_j$, using standard notation for the electric field and the polarization. ...
1
vote
2answers
130 views

Why isn't resistance proportional to distance squared

Here we have a wire. At both ends there is an equal and opposite field caused by a chemical reaction. So, if we decrease or increase the distance between the two points, the strength of the field ...
2
votes
1answer
42 views

Protect drone from lightning [closed]

I am designing a dirigible, robotic drone. It is basically a polyurethane airship, approx 3.6 m length and 2.1 m diameter. I am worried about lightnings: as far as I know, a Faraday Cage should be ...
2
votes
2answers
58 views

Basic of Capacitor

I've 2 capacitors; plate area, difference between plates and dielectric is same. Only thing is that the metal used in plates is different. Since the formula $\displaystyle C=\frac{\varepsilon A}{d}$ ...
0
votes
1answer
24 views

Why defects moderate (reduce) electric field?

I am running a simulation with drift-diffusion equation, Poisson equation and Fourier heat equation with a metal/insulator/metal structure. In my simulation, initially electric field is at the top of ...
1
vote
0answers
41 views

What is the most effective dielectric material known to man?

What is the most effective dielectric medium/material (highest breakdown voltage) known to man? Is it the vacuum? or are there any materials which could be more effective than the vacuum?
1
vote
0answers
42 views

Is the dielectric constant of an insulator always positive?

I know there are many examples of metals with a negative dielectric constant at optical frequencies. But what about insulators?
0
votes
0answers
50 views

Potential Around Suspended Particles

In my textbook, the classic example of a dielectric sphere suspended in a dielectric solution is solved, and a general form for the potential inside and outside of the potential is given without ...
0
votes
1answer
63 views

Dielectric boundary

I am trying to determine why electric field may be confined to a certain region if there is a large difference in the permitivity for example if electric field flows through water and then reaches a ...
0
votes
1answer
113 views

Is there a surface charge density?

Consider a dielectric sphere placed within a dielctric medium. There is a uniform electric field $E_0$ present throughout in the medium. Would there be surface charge on the sphere?
1
vote
1answer
47 views

Electrostatic field in a Dielectric equations misbehaving

Equation 1: $\int{\vec{E}.\vec{ds}} = \int\frac{\rho_{free} + \rho_{bound}}{\epsilon_0} dv$ (Gauss's Law) Equation 2: $\int{\vec{D}.\vec{ds}} = \int\rho_{free} dv$ (Gauss's Law) , but $\vec{D} = ...
1
vote
1answer
23 views

Relative perimittivity of conductor?

Why is the relative permittivity $\epsilon_r$ infinite for a conductor? Where does it come from mathematically and does it make physical sense?
2
votes
2answers
136 views

Gauss' law question

It's actually a teaching conflict at my school. They said that $$\text{Flux}=\frac{q}{\varepsilon_0}.$$ Say for a point charge at the centre of the sphere and let's say we not put water into the ...
0
votes
0answers
75 views

Force between two charges containing several dielectrics between them

The following question is quite similar to mine. Dielectric modification of electrostatic equations? However, the answer does not prove satisfactory to me. The formula given in the above problem ...
0
votes
0answers
56 views

Question on dielectric sphere

The question is: Suppose the field inside a large piece of dielectric is $E(0)$ so that $D(0) =$$\epsilon(0)E(0)$ + $P$. Now a small spherical cavity is hollowed out of the material. Find the ...
1
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0answers
32 views

Intensity Poynting

Take a plane wave propagating in the $\hat{z}$ direction in a non-magnetic linear dielectric. The real electric field is then given by $$\vec{E}(r,t) = E_0\, e^{-k_i z}\cos(k_R - \omega t)\, \hat{x} ...
1
vote
1answer
253 views

What is the capacitance of parallel plate capacitor with different electrode material?

What is the capacitance of parallel plate capacitor with different electrode material? The capacitance of parallel plate capacitor depends on dielectric material, surface area, and separation between ...
2
votes
1answer
83 views

Energy Stored in a Capacitor with and without Dielectric

I have seen the equation $V = \frac {V_0}{K}$, but also the equation $V=\frac{1}{2}CV^2$. The values of C and V increase in the same linear ration with K (because $C=KC_0$). However, as the energy ...
0
votes
1answer
90 views

Capacitor with dielectric between the plates

Let's assume we have a capacitor of capacitance $C$ and potential difference $U$. After charging it we disconnect it. Then we put a dielectric between the plates. I know that capacitance will increase ...
1
vote
5answers
250 views

Difference between dielectric constant and dielectric function

I'm confused by the definition of dielectric constant. We all know that dielectric is function of wavelength, because materials respond in different ways depending on the energy of the light. But what ...
2
votes
0answers
82 views

Electric field of a capacitor in dielectric medium with weird size

I have been learning gauss's law in capacitor recently, recently I come up with this problem that I couldn't solve myself. If we have a capacitor,and a dielectric medium with half the volume between ...
3
votes
3answers
1k views

Electric field intensity in a dielectric inside a capacitor

In the question A parallel plate capacitor is charged from a cell and then isolated from it. A dielectric slab of dielectric constant $K$ is now introduced in the left half region between the ...
1
vote
1answer
72 views

how electrophoretic display like E ink retains particles on top of capsule without power?

how electronic ink display retains the particles on top of micro capsule when charge on electrode is released or when device is powered off? Doesnt that make particles loose on the dielectric fluid ...
3
votes
1answer
159 views

A dielectric sphere in an initially uniform electric field and representation theory of SO(3)

I learned recently that the highest order spherical harmonic required to represent the spatial distribution of decay products of a particle can be used to determine its spin, by using arguments ...
1
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0answers
47 views

Does all electrical insulator can be electrostatically charged?

Does all electrical insulator can be electrostatically charged, or insulator with only dielectric property can? Thank you.
0
votes
3answers
713 views

Relation between complex dielectric constant and resistance

I am having a real hard time understanding how I reach the expression that relates resistance and $\varepsilon''$ as the complex part of the dielectric constant. I was trying to follow a clear and ...
0
votes
0answers
222 views

Electric field intensity at the center of a small cavity in a large block of polarized dielectric

I'm having trouble with an exercise in my textbook. The question is: Determine the electric field intensity at the center of a small spherical cavity cut out of a large block of dielectric in which a ...
0
votes
2answers
128 views

Dielectric constant of water

I need the dielectric constant of water from $10^{-2}$ Hz to $10^4$ Hz. As stupid as it may seem, I cannot find much info. I've googled for days. All I can find is close to GHz. And the only info ...
2
votes
1answer
97 views

Why is more intrinsic carriers bad for high temperature semiconductors?

I'm taking a solid state course, and is currently on the subject of dielectrics. In one of the sections, concerning "Impurities in Dielectrics" the books says: "Impurities can also be used to make ...
1
vote
0answers
196 views

Complex polarizability of a dielectric sphere in a homohenious electric field

It is well known that complex polarizability of uniform dielectric sphere with radius $r$ and complex permittivity $\hat\epsilon_{in}(\omega)$ placed in a medium with complex permittivity ...
0
votes
1answer
5k views

Dielectric Constant or Permittivity of Metals

I'm wondering what the dielectric constant or permittivity of metals is --particularly copper. Do metals have an infinite permittivity?
0
votes
1answer
75 views

Capacitors in parallel and dieletric [closed]

I'm trying to solve this problem: Two capacitors of capacitance $C_1=200pF$ and $C_2=1000pF$ are connected in parallel and loaded to a potential difference of $400V$. Subsequently the space ...
0
votes
0answers
13 views

Is this configuration correct for this spherical capacitor? [duplicate]

This capacitance contain 4 dielectric as shown in the figure dielectric 1 in half sphere and 2,3 in for 1/4 of the sphere and the fourth one in the last 1/4 of the sphere as shown and I want to find ...
5
votes
3answers
3k views

Real and imaginary parts of dielectric constant vs refractive index?

So for a complex dielectric constant $\epsilon = \epsilon_a + i\epsilon_b$, the wave vector and index of refraction are related to it through $k = \frac{\omega}{c}n$ and $n = \sqrt{\frac{\mu ...