Dielectric Definition and 732 Threads

we have a non magnetic but anisotropic dielectric medium which has the following relationships between D and E Dx = k1*Ex, Dy = k2*Ey, Dz = k3*Ez we have to show that waves propogate in the z-dir'n at one speed only. I can't get the wave eq'n to fall out. Usually you just use...

I wanted to use air as the dielectric for a capacitor for energy storage for aircraft. My thinking was that we could charge the capacitor on the ground and leave the capicitor open to the flowing air in flight. As long as the density of the flowing air remained the same, the capacitance would...

We have a dipole in a vacuum cavity inside an otherwise infinite LIH dielectric. We assume form Vin = Arcos(theta) + B/(r^2) * cos(theta) Vout = C/(r^2) * cos(theta) We are told that "as r tends to 0 the field must approach the dipole field". I'm not sure if they are talking about the...

A parallel-plate capacitor has rectangular plates of length L = 19 cm and width W = 3 cm . The region between the plates is filled with a dielectric slab of dielectric constant K= 4 which can slide along the length of the capacitor. Initially, the slab completely fills the rectangular region...

Dielectric Strength problem. Please Help! :( If anyone can let me know if I went about this right, I'd appreciate it, as well as any advice. The dielectric strength of an insulating material is the maximum electric field strength to which the material can be subjected without electrical...

Dear all, i am a bit confused with a very simple equation connecting refractive index of water and its dielectric constant for visible range of wavelengths and room temperature. i hope, You can help me as we know, the refractive index 'n' can be defined as n=sqrt(epsilon*mu)...

A slab of copper is thrust into parallel plate capacitor as shown in the figure. a) What is the capacitance after the slab is introduced? This is like two capacitors in series so C_{1} = \frac{\epsilon_{0} A}{d-b-x} C_{2} = \frac{\epsilon_{0} A}{x} when added it yields...

1. Basically, we have coaxial cable with an inner wire of radius a, perfectly conducting, straight and infinitely long, with radius a, surrounded by an outer hollow cylinder, also made from perfectly conducting material, having inner radius b and outer radius c. The hollow cylinder functions...

I wanted to find the dielectric constant of different materials placed in a parallel plate capacitor using the equation: K = \frac{E_{dielectric}}{E_{original}} Where E = \frac{V}{d} I would use sensors connected to a computer to measure the voltage and i could easily measure the...

Hi, I'm currently an A2 student and was wondering is it possible to find dielectric values for different materials placed within parallel plate systems. I have an idea but i think doing this is more complicated than i expect. I found the equation: k=Cd/epsilonzero*A d = distance between...

I konw that the defect centers in a dielectric contribute to the electric polarization and thus affect the permittivity.If there is any microscopic theory can derivate the relationship between the defect centers and the permittivity?

Electric energy of a dielectric sphere! Hi there, I have attempted a question, I was just seeing if some one can go over it and check if it is ok! Q. The Electric field E inside a dielectric sphere placed between the plates of a large parallel-plate capacitor is uniform. Given that the...

Total energy of a dielectric sphere please help! I have a problem that I can not do after searching the net and looking through my notes and textbook. I think it is a basic electomagnetic field question but i just can't get my head around it. The question is: The electric field E inside...

Hi all, I am sorry this could sound like heard many times before, but I am trying to understand this problem and found nothing in my physics books. If I put a small dielectric (bit of paper) into an electrostatic field (for example generated by a rubbed plastic rod), the paper will be...

If current densities are given in a perfect dielectric medium having \epsilon , \mu I have to find the power dissipated per unit volume, the electric field energy density, and the magnetic field energy density everywhere. Can I get help with equations?

suppose you had a capacator and a free to move dialetric, which was outside of it, and you attatch a voltage to the capacator. the dialetric will move in. however, does anybody know what force and where the force is that causes the dialetric to move in?

Hello Here's a situation I would like to discuss... Suppose we have an ideal parallel plate capacitor which is filled with air (or vacuum) with permittivity = 1. Now if a dielectric slab of width equal to the space (d) between the plates is inserted into the space between the plates, it...

I'm a little confused. My source says the dielectric constant for water is 80. Then I have the equation that gives the index of refraction as n=\sqrt{\epsilon_r} (since it isn't very magnetic). But the index of refraction for water is 1.33. What am I missing?

I am not sure if I have done the following problem correctly. To start, I do not know how to prove the electric field must be directed radially. Assuming this is true, then the magnitude of the field must be uniform along any spherical boundary (otherwise we could form a nonconservative loop...

Hey Guys, I was just doing a question on capacitance and i was wondering since capacitance is usually determined by a fixed formula which is dependent on the di electric material that is contained within a capacitor.. However it struck me that a capacitor does not neccesarily contain...

I need a little help on an E&M problem I'm working on. A dielectric slab suspended in free space has a time dependant, non-uniform electric field inside of it (it was given in the problem, but I don't have it with me right now). For the material \mu=\mu_0 and \epsilon=2.56\epsilon_0. I need...

I'm having trouble finding reliable data on the dielectric constant of helium(4) gas as a function of temperature, from 4K up. Grateful for any help

How do I find the reflectivity of a combination of ice on top of water(infinite half-space) as a function of the thickness of ice? I know how to find it for each material, it's just rho = ((root(dielectric constant)-1)/(root(dielectric constant)+1) )^2. I'm given dielectric constants for both...

This is one of my homework problems that I am stumped with: A parallel-plate capacitor with only air between the plates is charged by connecting it to a battery. The capacitor is then disconnected from the battery, without any of the charge leaving the plates. A) A voltmeter reads V_1...

Hi tide. question. What is the point in using a dielectric. I was doing a problem in the physics book and it showed that when you use a dielectric, the amount of energy stored in your capictor decreases. Wouldent you want to store the MOST amount of energy in your capacitor? So why bother...

Help Plz... Dielectric Properties Hii.. I am a new member of this forum. I wish to know about dielectric properties of materials. Do they change with the variation of frequency of RF wave, if the materials are exposed to RF waves? Please assist. Thanks in anticipation, Mahfuz

Hi everybody. I know a little about phonons in a lattice such as semiconductors, which are energy quanta of the vibrational states of the crystal, but I can't figure out how a phonon can exist in a dielectric or even in a non monocristalline material. Can somenone help me or advise me a book on...

The electric field between the plates of a paper-separated (K=3.75) capacitor is 9.41E4 V/m. The plates are 1.75mm apart and the charge on each plate is 0.775E-6C. Determine the capacitance of the capacitor and the area of each plate? I got the voltage by V=Ed. and that came out to 164.675...

Where should I go to identify some very basic dielectric properties of the following materials: PVC, polyethylene, polystyrene, glass, acrylic, nylon, polyester?? I'm trying to determine whether these materials have negative or positive charges and how the charge is determined. My son, a 4th...

Hello! I'm making some home-made capacitors for an up-coming lab, and I was thinking of using Market Basket/DeMoulas' plastic kitchen bags as a dielectric. I'm really hoping to use it because the packaging info includes the thickness of the bag (19 micrometers), which should increase the...

I would dearly like to know what material has the highest relative dielectric constant and how much is it?

I have been reviewing the method of images for electrostatic problems and noticed the following: Textbooks point out that to use Gauss' Law successfully there must be geometric symmetry that makes the Efield constant over some reasonable surface. I thought this was just to make the math...