Questions tagged [insulators]

Electrical insulators are materials through which electric charge does not flow freely. Insulators have high electrical resistivity.

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38 views

Why don't we use tubes of vacuum as insulator in houses? [closed]

If vacuum is a good insulator, why don't we use tubes of it as insulator in houses?
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Why is electric field in an insulator non zero?

I had read from several sources that electric field inside a conductor is zero. This is attributed to the fact that the electrons are loosely bound to the nuclei and they are free to rearrange ...
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Does the Mott metal-insulator transition occur with increasing or decreasing density of valence electrons?

When reading about the Mott metal-insulator transition, it has not become clear to me if the transition from a metal to an insulator occurs with increasing or decreasing density of valence electrons. ...
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Metal-insulator transition (material properties)

When studying about metal-insulator transitions, I was wondering which material properties can give direct information about this phenomena. Also, what information can be derived from these properties....
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Gauss's law and electric field inside spheres and shells

I have a question regarding the electric field inside a sphere and shell and I know the result but don't really understand why it is what it is. Lets say there is a shell with radius $R$ and that has ...
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Conductors and Insulators from the point of view of Quantum Mechanics

So, I was watching this lecture of MIT 8.04 Quantum Mechanics course and at around 38:00, the instructor starts discussing periodic potentials to predict the properties of conductors and insulators. ...
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51 views

Can a conductor be uniformly charged?

I have been reading in books that charges on a conductor resides on its surface and that for a body to be uniformly charged it has to be an insulator.Is it true?If yes does it mean we can consider a ...
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Does the Mott insulator exist?

The Mott insulator is a system that due to strong electron-electron interactions is an insulator which be a metal by formal charge counting of electrons in the unit cell. Often, the Mott insulator is ...
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1answer
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Joining two insulators at different potentials with a conductor

If two insulators are connected by a conducting wire, will the charges flow if they are different potentials? According to me, as the charges can't enter the insulators, charges only get distributed ...
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Comparing energy band diagram for metals, semiconductors and insulators

The energy band diagram is a model for describing why an insulator is not a good conductor compared to a semiconductor: in the first case, electrons would need to pass a very large band gap in order ...
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3answers
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How do that charge gets transferred while rubbing?

We all have studied that on rubbing a glass rod with silk or human hair, the two get charged with opposite polarities. What confuses me is that since both glass and silk(or hair) are insulators, they ...
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What does the subindex $x$ in $\text{Bi}_{1-x}\text{Sb}_{x}$ mean?

I am currently reworking our condensed matter lecture. We shortly discussed topologic insulaters at the example of $$\text{Bi}_{1-x}\text{Sb}_{x}$$ I am not sure what the $x$ stands for. Normally ...
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An idea to make a very high capacity battery

If you make an atom ion, it take/give electron from another atom but if you put a ion that is opposite charge of it to the next of the atom(but atom's won't touch each other), it can be stay at that ...
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Wiedemann-Franz law generalized to quantum Hall effects in electronic systems

Wiedemann-Franz law states a relation in a conductor between the thermal and electric conductivities by their ratio as $\kappa/\sigma=LT$ where $T$ is the temperature and $L$ is the Lorenz number ...
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Grounded Conductors and Charge

Not HW, just something that popped up in my mind during a shower XD Consider a configuration consisting of an insulator that has been charged negatively by friction, and a conductor placed nearby. ...
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What makes electrons 'more free or less free' to move around?

I understand that conductors allow electron flow because their valence electrons are 'free' to move around.. But what exactly determines this 'freeness' and the lack thereof that separates conductors ...
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What exactly happens when a charged conductor comes into contact with an electric insulator?

Let us say we have a negatively charged conducting sphere: If we put an insulator into contact with the sphere: Would the negative charges located in the contact region transfer from the surface of ...
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1answer
153 views

Does an insulator always contain the Fermi surface in the 1st BZ

I'm looking for a clarification about the classification of metals and insulators; is it correct to state that if the Fermi surface is contained into the first BZ, then the material is an insulator, ...
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1answer
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Metal-Insulator from number of atoms in the basis

I have an issue understanding what A&M means while saying this in chapter 12: It is a reassuring exercise to go through the periodic table looking up the crystal structure of all insulating ...
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1answer
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How does charge movement vary between insulators and conductors?

I've been reading A Student's Guide to Maxwell's Equations by Daniel Fleisch, and he states: in nonconducting materials (called "insulators" or "dielectrics"), charge does not move freely, but may ...
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What makes a topological insulator topological?

I understand that a topological insulator is one with an insulating bulk and conducting surface but I don't understand why or how the topological part comes into it. All of the resources I've found ...
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190 views

Location of free charge in insulators

I'm going through the introductory section to Electrostatics in Materials in Griffiths, and I have a question that I can't seem to find a satisfactory answer to. If I have an insulator with free ...
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Why electron can go through PVC insulator

I connected a PVC insulated alligator clip test lead to a 12V (give 20V) DC power supply positive terminal and a multimeter. After that I connected an other one to the multimeter ground, and a third ...
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1answer
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Semiconductor and Fermi level in semiconductor

According to band theory, at $T=0\ \text{K}$ the Fermi level of an intrinsic semiconductor lies in between the valence band and the conduction band, while in the case of an insulator it lies near the ...
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1answer
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Is it absolutely insulating in its interior of topological insulator?

If putting a 3D topological insulator (TI) into a sandwich testing structure (electrode-TI-electrode), can we detect any leakage current in its interior like the ordinary insulator? Is it absolutely ...
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What are the Possible Dangers of an Overheating Household Wire? [closed]

Can anyone tell me any possible dangers/risks that could happen if a wire overheats even if it's insulated properly?
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New black Van in South Florida - To insulate or Not? Radiative Cooling effect?

I'm not homeless, I'm just frugal and trying to drive a lot less.. maybe I'm adventurous. :) Anyways, I've been working , eating and sleeping out of my new Black van. The van is brutally hot during ...
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Electrical vs Heating Insulation

Let's say we have a 120V cable and a 600V cable, this means that the 600V needs more electrical insulation to prevent the insulator from exceeding its dielectric strength. But in the other case, the ...
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811 views

Why High Voltage Power Lines need more Insulation than a low one?

"A 400 kV cable requires less insulation than a 240V cable." This was regarded as False in one of my question papers, but why? Doesn't a higher voltage means, lower current(P=V. I) and a lower ...
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379 views

Semiconductors/insulators: Why is the fermi energy between the valence and conduction band?

Ive asking myself a question on the fermi-energy. The fermi-energy is defined as the maximum energy which an electron, following the Pauli-rule, can have at T=0. In semiconductors and insulators the ...
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238 views

Why don't insulators conduct electricity? [closed]

I have been taught in school that because of the high energy band gap (approx. $9~\text{eV}$ or more) of an insulator, electrons can't jump to the conduction band. But also $1~\text{eV} = 1.6 \cdot ...
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91 views

Could one make an electrostatic “permanent magnet”?

Could one make a negatively-charged insulator with the extra electrons trapped all the way through its volume by building it up layer by layer with electrons "sprayed" onto each layer as it was ...
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1answer
112 views

Is diamond able to conduct electricity given 5.5 eV of energy? How do we then identify insulators and semiconductors?

I have learnt that the band gap for diamond, an insulator, is $5.5\:\rm eV$. Does this mean that diamond is able to conduct electricity if we give it this immense amount of energy (let's assume we do ...
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628 views

Electric fields and insulators

Will the electric field of an induced dipole in an insulator match the electric field inducing it but in the opposite direction? I have 2 counter theories: Let's say I place an insulator (and let's ...
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Effect of humidity on removing excess charge from objects [duplicate]

The usual answer to the question "why electrostatic discharge happens more often on dry days" is that water - due to its polarity - has the tendency to remove the excess charge. But I do not ...
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1answer
28 views

Ways to generate long-lasting charge on materials surface?

First off, I am no physicist, please don't judge me if I said something wrong. I read that insulator surface can carry a static charge by rubbing against another insulator with a different electron ...
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1answer
47 views

Material with fairly high resistivity, but allows flow of charge

Is there a material with fairly high resistivity (at least semi-conductor level), but also allows the flow of charge through it (and subsequently to the ground)? The flow of charge does not need to be ...
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245 views

If vacuum is an insulator, then why do charges flow inside a vacuum tube?

Since vacuum or free space is used as insulators in capacitors, how is it possible for charges to flow inside a vacuum tube?
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4answers
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Are materials which are bad at conducting heat always bad at conducting electricity also?

When defining a material's conductivity, we usually consider its conductivity of heat and conductivity of electricity separately. However, I realize that materials like metal conduct both heat and ...
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140 views

Insulator behavior of large U limit in Hubbard model

I am now learning the many-body physics and having some questions about the insulator behavior of large $U$ limit for the Hubbard model : \begin{equation} H = -t\sum_{\left\langle {i,j} \right\rangle,...
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2answers
604 views

Calculating temperature of insulated container over time

Experiment In Science Olympiad there is this competition called Thermodynamics. In thermodynamics, we have to make an insulating box that is smaller than 15cm by 15cm by 15cm. This box will have a ...
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1answer
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Does the shiny side of foil keep food warm? [duplicate]

As the title asks, does the shiny side of foil really insulate or keep food warm when facing inwards? I've heard that the shiny reflective surface of the foil reflects the infrared energy. Is this ...
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1answer
192 views

Is electron-hole pair generation and recombination process in insulator same as semiconductors?

I was trying to understand the electron-hole generation and recombination process in materials. However, most of the sources explain the phenomenon by using semiconductors through the energy-band ...
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1answer
825 views

How do insulators lose their charge?

Some theoretical questions that got me confused during physics lecture today. bringing a conducting balloon to a negatively charged rod close will allow the conducting balloon have positive charges ...
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1answer
203 views

Why we assume a negative charge inside a cavity of non-conductors?

The electric field of a spherical non-conductor, with uniform charge density $\rho$ is, $$E_s(r)=\frac{\rho r}{3\epsilon_0}$$ It is mentioned in a lot of places that the electric field inside the ...
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1answer
400 views

Why don't insulators attract even if charged?

I understand that/ obviously, opposite charges will attract? However, I am still slightly confused about what happens if an insulator becomes charged. How come an insulator, which is charged, will ...
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1answer
3k views

What is the basic difference between insulator and dielectric? [closed]

I just want to know the similarities and dissimilarities between them.
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311 views

Why aren't all insulators transparent, since they have a large band gap?

According to Floris' answer in this link, diamonds are transparent as they have large band gaps while graphite is black as it is a conductor. As electrical insulators generally have a large band gap, ...
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1answer
366 views

Is wearing an insulated metal armor against a lightning safe?

Related: Is wearing metal armor during lightning safe? only partially answer my question. During a discussion in my question in Worldbuilding, this answer explain that as long as the metal armor is ...
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1answer
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What happens to any insulator when it is placed in any external electric field?

This is in the case of a conductor: I want to know what happens in the case of insulators.