Dielectric Definition and 676 Threads

Homework Statement Find the capacitance of the capacitor shown in the figure. Asume H << L. http://imageshack.us/a/img39/1935/capacitor.png Homework Equations Capacitance of a plate parallel capacitor with a dielectric material e: eA/H where A denotes the area of the plate, and H...

PROBLEM: I am asked to consider a parallel polarized planar wave with frequency ω is normally incident on a dielectric boundary. The incident time average power flux P_i = 100 w/m^2. The first medium is free space and the second has vacuum permeability but ε=4ε_0. We are also given that the...

Imagine a dielectric cylinder placed in a uniform magnetic field parallel to its axis. Then we make it rotate around its axis. The nuclei and electrons should feel a radial lorentz force because of their rotation around the axis of cylinder.The forces applied to electrons and nuclei are in...

Homework Statement An isolated charged parallel-plate capacitor with the plate separation d=2 mm and area of A=10 cm2 is initially empty. One slides a polystyrene dielectric slab with thickness equal to half the plate separation and with only half the area of the plates into the region between...

How can we show that the bound charge in a homogeneous linear dielectric is proportional to the density of the free charge. I have a handful of equations but still I can't work this out.

U = (1/2)CV^2 = (1/2)Q^2 /C Increasing C while keeping Q constant (isolated capacitor) will decrease the energy contained in the capacitor by and amount X Where does this X energy come from? Case 1 (slab polarizes immediately when it crosses the electric field of the plates) The capacitor...

Homework Statement I'm given the refractive index of a piece of glass: $$n(\omega)=A+B\omega$$ And I have to find the speed at which a pulse of radiation will travel through the glass at an angular frequency $$\omega = 1.2 \times 10^{15} s^{-1}$$ I also have A = 1.4, B=3.00 x 10^-17. Homework...

Homework Statement we put a dielectric hemishphere with radius (a) and dielectric coeeficient(k) on an infinite conducting plane.the system(hemsiphere and the plane) are in a constant electric field E0. find the surface charge distrubution on the plane as a function of (r). and explain what...

What is the differecenbetween insulator and dielectric ? hello friends , please clear me the difference between them.

I'm looking for some sort of dielectric coating that can be used at high temperatures. I'm working on trying to create a voltage point charge in a high temperature steam environment using a coated accupuncture needle. The goal is to be able to coat the needle thinly and uniformly, leaving only...

Homework Statement For a dielectric slab of relative permeability er fills the space between z = ±a in the xy-plane, and contains uniform density of free charge ρf per unit volume. Find E, D and P as functions of z. Homework Equations P = εoXeE D = εrεoE ∇×P=εoXe(∇×E) = 0...

Force act on dielectric slab on inserting between the parallel plate = [8.85 * 10^-12]b(k-1)(V^2)/2d where b = width of the plate , d = distance b/w the plates , V is the constant potential difference across the plates and k = dielectric constant Which force is acting on dielectric...

Two capacitors have the same plate separation, but one has square plates and the other has circular plates. The square plates are a length L on each side, and the diameter of the circular plate is L. The capacitors have the same capacitance because they contain different dielectric materials...

Homework Statement Consider a long cylindrical coaxial capacitor with an inner conductor of radius a, and outer conductor of radius b, and a dielectric with a relative electric permittivity or dielectric ε(r), varying with the cylindrical radius. The capacitor is charged to the voltage V...

How does the voltage on a capacitor vary if the dielectric is an ionised gas?

i was studying incidence of EM wave at a plane dielectric boundary and encountered equations in the attachment . I just want to know if n2 > n1 then electric field amplitude at the boundary increases . So from where does this extra value comes ? n1 and n2 are intrinsic impedances of 1st and...

Homework Statement A capacitor consisting of two parallel plates of area A = 7.3 m2 and spacing d = 0.150 m is filled with two parallel slabs of dielectric material of equal thickness and with dielectric constants 1 = 3.20 and 2 = 7.50, respectively. What is the total capacitance? k1 fills...

Hi everyone I have a problem to solve, I already simulated it with FEMM, but I wonder if it is possible to find an analytical solution. Let's say that there's a small coil (100 turns) around a pipe (2in diameter), the pipe is filled with air. This pipe is located inside a bigger pipe...

Lets say There is a capacitor with the are of Plates A and the distance between the plates say is 5m if a dielectric of similar dimensions except the width is 3m is filled between the Capacitor plates how to calculate the new Capacitance ??

Homework Statement Use Gauss' law to find an expression for the electric field within a charged parallel plate capacitor with two layers of dielectric materials (?r1 and ?r2). (See attached image, this is for question 2a). The Attempt at a Solution My approach would be to split the...

i'm reposting this question as nobody answered it previously. please answer it this time. in given type of arrangement we normally take it equivalent to two capacitors(plate 1 and surface 2) and (surface 2 and plate 3) in series. My question is that a capacitor is formed with two plates of...

Okay so I have a parallel-plate capactior k=5.5 Area= .034m^2 Plate Separation= 2mm If the Electric Field falls short, the capacitor will burn up if exceeding 200kN/C. It's asking for the max energy stored by the capacitor. My attempt was lame. I tried using C= (ε0)A/d and...

To anyone that can help me, Hello everyone. I am student from Mechanical Engineering and I am very new to electronic field. I currently doing my final year project which is developing the high voltage discharge circuit for the DBD plasma. The middle electronic elements is the representative...

Dielectric constants in different directions -- does this make sense? So I'm trying to analyze a scenario in which I have a plane wave incident (from, say, some medium with permittivity and permeability ε_1 and μ_1), on a plane of a dielectric material that has an anisotropic permittivity: in...

Homework Statement Hey all, I want to find the potential due to a point-like (mathematical, not physical) dipole inside and outside of a sphere made of dielectric material with dielectric ε. It's of radius R. Outside the sphere is vacuum.Homework Equations The Attempt at a Solution Inside...

I had always thought that a capacitor with a dielectric transmits AC precisely because it polarizes in response to the applied field. To tell you the truth, I realize now that I had two different views on how this process works: One: the AC is oscillating on both sides of the dielectric...

If a capacitor's dielectric partially breaks down, as in some of the material has ionized and acted as a conductor, will there still be a capacitance to the component? Say its a high frequency AC signal on a capacitor with a small part of its dielectric material in a breakdown state. My...

Hi everyone, From what I understand if you had a time varying magnetic field inside a dielectric it will induce a time varying electric field according to Faraday's Law: \nabla\times\mathbf{E}=-\frac{\partial \mathbf{B}}{\partial t} My question is will the dipoles in the dielectric then...

Homework Statement http://img99.imageshack.us/img99/763/prob45.gif Fig. 1 and 2 show a dielectric slab being inserted between the plates of one of two identical capacitors, capacitor 2. Select the correct answer to each of the statements below (enter I for `increases', D for `decreases', or...

If you have a simple circuit with only a battery and a parallel plate capacitor with a dielectric, what exactly happens when the battery is turned on? Also, if the voltage of a capacitor with a dielectric is less than the EMF of the battery, what happens to the rest of the voltage? One...

Homework Statement How large proportion of wavefront's power penetrates dielectric material's surface in a perpendicular collision from air. The only parameter that I have is \varepsilon_r = 16 where \varepsilon_r is the relative permittivity.Homework Equations \varepsilon = \varepsilon_r...

Homework Statement A 6.8-nF parallel plate capacitor with a sheet of Mylar (κ = 3.1) filling the space between the plates is charged to a potential difference of 160 V and is then disconnected. (The initial capacitance including the dielectric is 6.8 nF.) (a) How much work is required to...

I have seen some examples where a system has a resonance frequency, and, when the system changes, its Q factor also changes, and so the resonance frequency shifts, and this shift can be measured to detect the change in the system. An example I can think of is very sensitive mass measurement...

Homework Statement Two parallel plates, each having area A = 3118cm2 are connected to the terminals of a battery of voltage Vb = 6 V as shown. The plates are separated by a distance d = 0.35cm. You may assume (contrary to the drawing) that the separation between the plates is small compared...

Hello, I have been trying to better understand the effects of dielectrics in resonant cavities. I read that the addition of a dielectric in a resonant cavity will reduce the resonant frequency of the cavity. My questions: Is there any relation to the reduction of the resonant...

Homework Statement A conducting sphere of radius A has a charge +Q on it and is surrounded by an insulating material whose dielectric constant varies with radius according to εr = 2exp[-(r/a-1)]2. The dielectric has a spherical outer boundary B. Find the values of D, E, P, ρ as a function of...

So for just vacuum in between one could say F=q*E = (σA)*(σ/2ε0) = A*σ^2 / (2ε0) Alternatively, F = dU/dx, where x is the separation. U = 1/2 CV^2 = 1/2 QV = x*A*σ^2 / (2ε0). To get V, we just add up pieces of E-field*distance. But now let's say part of x is a dielectric of thickness t...

Homework Statement consider a long cylindrical dielectric shell of inner cross-sectional radius a , outer radius b, and constant volume charge density raw zero . THe potenials of the ineer and outer surfaces of the cylindrical shell are held at potentials 0 and V respectively as shown in the...

I know that I should do my homework, but I lost all my notes because of the flood brought by "Sendong" a storm in the Philippines. I just need the equations to be used to solve the problem that was given to us. So here it is: A parallel plate capacitor has a capacitance of 7MF when filled...

i was reading Random Phase Approximation and encouter with dielectric function ε(q,ω)= 1- v(q) ∏(q,ω) where v(q) is coulumb potential and ∏(q,ω) is density-density correlation function without coulumb interaction now i do not understand this dielctric...

A capacitor is connected to a HVDC power supply which provides a minimal current. When the volage reaches the capacitor plates the dielectric material in the capacitor polarizes. Now, if there existed a barrier between the dielectric and the capacitor plate the capacitor could theoretically...

hi, i have seen on another topic here that the refractive index equals the square root of the dielectric constant. from datasheet values we have... water refractive index = 1.333 dielectric constant = 80.1 Without even doing the calculation its obvious that the square root of 80.1 is not...

Hello! Electric force is inversely proportional to the dielectric constant. In a textbook, this is said to be forty-fold greater for water than the phospholipid membrane. As such, ions are unlikely to cross the plasmamembrane. I assume this has something to do with preferring to stay in...

Hi all, An electrolytic capacitor has 2 AC sources connected to it, 1 at each plate. The AC sources are 180 degrees out of phase and have a high impedance which limits current in the nA range. Even though each plate should have AC on it which is 180 out of phase the voltage at each plate...

When the dielectric in a capacitor polarizes does it effect the leakage current through the dielectric? Just wondering, if you had a capacitor with a lossy dielectric and you were able to polarize the dielectric would the leakage current drop? Can anyone give me any links for further...

Why are optical traps constructed using beads that are made of dielectric materials? What property of dielectrics is being employed here? Would a non-dielectric material still experience radiation force from photons? Thanks!

Here is the problem from I.E.Irodov's Basic laws of electromagnetism. An infinitely large plate made of homogeneous linear isotropic dielectric with dielectric constant \epsilon is uniformly charged by an extraneous charge (see footnote) with volume density \rho > 0.The thickness of the...

The problem is as follows: Two long coaxial cylindrical metal tubes (inner radius a, outer radius b) stand vertically in a tank of dielectric oil (susceptibility χe, density ρ). The inner one is maintained a potential V, and the outer one is grounded. To what height (h) does the oil rise in the...

Homework Statement This was done on my Physics II class, ans the Professor has'nt want to explain it to usA 2 Circular Metallic Plate Capacitor, maybe of a diameter of 15cm, was connected to a constant sourch of DC voltage until it was charge to 10Volt, after this the source was DISCONNECTED...

Homework Statement Dual plate capacitor with two dielectric slabs placed between the capacitors and a battery supply's a voltage across the capacitors. The slabs are not equal in dielectric permeability. What is the charge at the interface of the two slabs? Homework Equations The...