# Dielectric constant Definition and 20 Discussions

The relative permittivity, or dielectric constant, of a material is its (absolute) permittivity expressed as a ratio relative to the vacuum permittivity.
Permittivity is a material's property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum.
Likewise, relative permittivity is the ratio of the capacitance of a capacitor using that material as a dielectric, compared with a similar capacitor that has vacuum as its dielectric. Relative permittivity is also commonly known as the dielectric constant, a term still used but deprecated by standards organizations in engineering as well as in chemistry.

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1. ### Find the charge density on the surface of a dielectric enclosing a charged sphere

The net Electric field(inside the dielectric): $$E_{net} = \frac{1}{4\pi \varepsilon_0 \varepsilon_r} \frac{q}{r^2}$$ $$\vec E_{net} = \vec E_{applied} - \vec p$$ where p is the polarization vector. let charge ##q_{-}## be present on the inner surface of dielectric and ##q_{+}## on the outer...
2. ### Wavelength in relation to the Dielectric Constant Dk

Hi, On slide 9 of this presentation: http://www.globalcommhost.com/rogers/acs/techsupporthub/en/docs/MWJ_webinar_June20_2017_JC_microstrip_coplanar_stripline_final.pdf it states the signal wavelength can be changed with dielectric constant Dk. As far as I understand the wavelength and the...
3. ### Phase lag of light in materials

There are 5 fantastic videos in this website: http://www.alfredleitner.com/ He is a very good educator and it is also very good to see those authentic experiments and aparatus. Anyway, in the following one at exacly 8:00 minutes he says that the phase lag induced by the dipole is always 90...
4. ### Difference between polarization and the dielectric constant?

Hi everyone, When an electromagnetic wave passes through a material, then depending upon the atomic structure of that material it polarizes that material. There is another definition of polarization in physics which says that polarization is the direction of oscillating electric field in EM...
5. ### Modeling the Driven Damped Oscillations in a Material

Homework Statement [/B] Let us assume that neutral atoms or molecules can be modeled as harmonic oscillators in some cases. Then, the equation of the displacement between nucleus and electron cloud can be written as $$\mu\left(\frac{d^x}{dt^2}+\gamma\frac{dx}{dt}+\omega_0^2x\right)=qE.$$ where...
6. ### Theoretical ξr of a molecule from the absolute configuration

I am wondering if anybody knows how to calculate the theoretical relative permittivity of a molecule (1) using the theoretical configuration and values that are easily accessible (2). I am also wondering what the technique would be. In my pharmaceutical reaction class and also O-chem 2 we have...
7. ### Confusion with constant voltage and dielectric

Homework Statement Consider a conducting sphere with radius ##R## connected to a voltage source of ##V_0## volts. If the sphere is then covered by a dielectric spherical layer of radius ##9R## calculated the relative permitivitty ##\varepsilon_0## needed so that the field in the empty zone...
8. ### I EM Radiation of "Permanent" Molecular Electric Dipoles

Suppose I were to subject a polar molecule to a high-frequency electric field. The polar molecule responds to the high-frequency electric field and thus it has a time-varying electric dipole moment vector. If we treated this as a classical electric dipole, it would be expected to radiate some of...
9. ### Capacitance with smoothly varying dielectric in 1D

Dear all, I am trying to find the capacitance of a parallel plate structure that comprises a spatially varying (linear) dielectric in one dimension. I have two methods of solving this which give different answers, and I am not sure which is correct. I consider the dielectric region to be...
10. ### Boundary conditions in dielectric problems

Q) A conducting sphere of radius R floats half submerged in a liquid dielectric medium of permittivity e1. The region above the liquid is a gas of permittivity e2. The total free charge on the sphere is Q. Find a radial inverse-square electric field satisfying all boundary conditions and...
11. ### Coupling capacitance between interconnects in VLSI

Hello all, I'm trying to measure the effect of adding charges in the silicon dioxide separating two interconnects in VLSI circuits and how it will effect the coupling capacitance between these two wires. How can I measure this effect ? The VLSI circuit I'm working on has frequency of 500...
12. ### A How to start my reading for 2D screening models

Hi All, I needed some help or guidance starting my MSc reading, as there is tonnes of literature out there and it's difficult to understand what is necessary. I am beginning to look at applying screening models to a 2D system, such as the Thomas-Fermi continuum screening model, to a 2D system...
13. ### Electric Potential at Center of Sphere

Homework Statement A solid conducting sphere of radius R and carrying charge +q is embedded in an electrically neutral nonconducting spherical shell of inner radius R and outer radius 9 R . The material of which the shell is made has a dielectric constant of 2.0. Relative to a potential of zero...
14. ### Layering different dielectric materials to increase breakdown voltage

This is a general question, not a homework question, and @berkeman said I should post it in the EE forum... I'm trying to get a better understanding of the relationship of dielectric constant (relative permitivity) to dielectric strength (breakdown voltage).I want to know what happens when you...
15. ### Sample smaller than parallel plates in capacitance setup

Hi, My setup for measuring parallel plate capacitance consists of an LCR meter and a parallel plate test fixture. The area of the parallel plates is much larger than the area of the samples I am measuring. From what I've seen in literature, and my physics classes, the sample area should be...
16. ### Building a Capacitor

Hi! I have to build a capacitor out of the following materials: 10 square feet of aluminum foil, 10 square feet of saran wrap (polyvinyl chloride), several sheets of paper, and tape to put it all together. I will only have about 30 minutes to manufacture my design. I have been researching...
17. ### Dielectric Constant

Homework Statement A parallel plate capacitor has a capacitance of 1.5µF with air between the plates. The capacitor is connected a 12V battery and charged. The battery is then removed. When a dielectric is placed between the plates, a potential difference of 5.0V is measured across the plates...
18. ### Investigating the water-ice electret

Hello all, I'm going to investigate the properties water when frozen in a strong electric field for a product I'm designing. A strong field will align the polar water molecules, and then they will freeze. I'm planning to create this strong field with a car battery attached to two parallel...
19. ### Dielectric constant in few-layer and in bulk materials

Why is the dielectric constant smaller in few-layer materials than in bulk materials?
20. ### Electric field using dielectric constant

Homework Statement What is the magnitude of the electric field due to a 6.0 x 10-9 C charge at a point located 0.025m from the charge? The charge and the point in question are located underwater (κ(water) = 80). Homework Equations I know that E = magnitude of electric field = kq/r2, where k =...