Insulator Definition and 126 Threads

Homework Statement An infinitely long solid insulating cylinder of radius a = 2.5 cm is positioned with its symmetry axis along the z-axis as shown. The cylinder is uniformly charged with a charge density ρ = 30 μC/m3. Concentric with the cylinder is a cylindrical conducting shell of...

When a charged body is brought near one end of a rod, opposite charge is produced at the opposite end of the rod. This is written in my book. Why is charge produced at only the opposite end?

Hi, Does anybody know a material which is a good thermal conductor and an insulator at the same time (at temperatures around 4 K) and is "easy" to fabricate? For e.g. sapphire fulfils the first two requirements, but is extrmely hard.

Homework Statement A new type of insulating board has been developed by that esteemed construction company Kaput Ltd. They warn that at extremely high heat fluxes it could be ignited, but they don’t think it’s very likely and it would take hours, so there’s no real risk! As an expert on the...

Homework Statement A solid insulating sphere of radius a = 5.6 cm is fixed at the origin of a co-ordinate system as shown. The sphere is uniformly charged with a charge density ρ = -494 μC/m3. Concentric with the sphere is an uncharged spherical conducting shell of inner radius b = 10.8 cm...

Is resistor a conductor or an insulator?

to get a 2D mercury telluride topological insulator, one has to construct a quantum well structure to get a bulk gap and most people use sandwiched structure with mercury cadmium telluride on top and the bottom. (so CdTe/HgTe/CdTe) and my question is can we get same or similar quantum...

Hi, I need help to understand these statements: The generators at the power plant can be operated as either, constant voltage source (CVS), or constant current source (CCS). To obtain a CVS, you spin the generator at constant speed. To obtain a CCS, you spin at constant torque. The CVS is...

I was wondering, what is the distinction made with problems involving either conductors or insulators with electrostatic problems. Is it that the electric field in an insulator doesn't have to be zero, whereas the electric field in a conductor is always 0?

Homework Statement A spherical insulator of radius R and charge density ρ = ρo/r2 where r is the distance from its centre. Find the electric field at a point inside and outside the insulator. Homework Equations EA = Qencl/εo The Attempt at a Solution What's throwing me off is...

Hi all, New here...I was wondering if anyone knows a formula to calculate the (insulation) resistance between two parallel conductors buried in an insulator. For example say 2 copper pins of 1mm diameter spaced 2mm apart over a 20mm length in a plastic (ptfe). The numbers/material are not...

Hi I am studying how the spin orbit interaction in certain materials can lead to topological insulator effects and realize it has something to do with the effects of the SOC on the band structure of the material (Bi2Se3), possibly due to the inversion of the valence and conduction band but I...

Imagine an electric field created by a electricity running through a looped wire. Leaving all other variables exactly the same, would the strength of the electric field inside the loop be less if the wire is insulated? Thanks!

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

why is it quite difficult to understand about conductor,insulator and resistor in parellel and series circuit?any way and method for easy understanding...help please...

I would like to find an insulator that can work in high heat and take a beating. A strong metal would be nice. It will be taking a beating and it will have to hold the copper in it form or the copper will flattened out

I am a bit confused about what actually makes something insulating. As far as I know a conductor has free electrons so when you put it in an external E-field these will move to terminate the external field thereby producing a currrent. But then I sat down and thought, why do charges pile up at...

I am curious to know, what make air in itself a good insulator? Just to clarify I am not talking about materials that trap the air and stop the convection current from moving, from a hot surface to a cold one. Is it because of the thermal capacity of air, which I believe is something like...

Why is it so important to claim that the topologically protected surface states are 100% spin polarized. Is there any connection between the degree of polarization and for instance transport properties, like the absent backscattering of these states at impurities?

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...

Hello, Just wanted to check my some of my reasoning to these. If anyone could confirm if these answer I got are right (or point me in the right direction if they aren't!) I'd really appreciate that. Thanks! 1. Homework Statement (No Relevant Equations, real, & Attempts at Solutions are...

I am working on a project that uses a Faraday cup. Its consists of a metallic cylinder(pipe like) with an electrode at the bottom.The ions enter the cylinder and hit the electrode.The resulting current is carried away from the electrode to an amplifier by a wire .The electrode that i am using is...

taking current from an insulator?? I am working on a project that uses a Faraday cup. Its consists of a metallic cylinder(pipe like) with an electrode at the bottom.The ions enter the cylinder and hit the electrode.The resulting current is carried away from the electrode to an amplifier by a...

I just some how fell into a wiki article about http://en.wikipedia.org/wiki/Insulator_%28electrical%29" and then read the following statement: The question is, why is it that there are no perfect insulators? I thought things like plast, wood, didn't allow electricity to flow through at all...

An infinitely long solid insulating cylinder of radius a = 5.3 cm is positioned with its symmetry axis along the z-axis as shown. The cylinder is uniformly charged with a charge density ρ = 45 μC/m3. Concentric with the cylinder is a cylindrical conducting shell of inner radius b = 14.2 cm, and...

Hey everybody! Let's say we have an infinite metal plate, and we apply voltage between two points, thus creating a potential. On this plate, we take a cutter and create a finite gap (filled with air), somewhere between the electrodes that apply the voltage. Simulations in ANSYS show that...

Is there a general formula to measure the amount of heat lost per second (Joules per second) given the surface area which the water covers and the width of the insulator material surrounding it?

What are the effective mass of conduction band (mc) and valence band (mv) of insulator material Al2O3. Kindly tell me your reference

Hi all, I am trying to run a simulation, and I have come across a theoretical question. Let's say that you have an electric charge producing a potential on a conducting surface (let's assume it's infinite). Now, if you make a crack in the surface so that there is a gap (filled with air for...

This is just a hypothetical questions, but... Would it be possible to have a capacitor so large that its able to store all the free electrons in the wire in the circuit its attached to? Then, this would mean all the free electrons have been removed from the wire, thus making the wire non...

Hey all, I'm using a peltier device for a cooling system I'm working on. The metal leads connecting the peltier to a power source keep falling off. I am looking to coat them with epoxy that must be a thermal insulator. It also MUST be an electrical insulator. The problem I've had is that...

I had been reading several articles on topological insulators (TI) including the Kane and Hasan's 2010 RMP. I am not very much clear about the Z_2 invariant TI. I mean, the even-odd argument proposed by Kane and Male (also argued by S. C. Zhang's group and Joel Moore's group in a different way)...

Homework Statement An infinitely long solid insulating cylinder of radius a = 3.2 cm is positioned with its symmetry axis along the z-axis as shown. The cylinder is uniformly charged with a charge density ρ = 22 μC/m3. Concentric with the cylinder is a cylindrical conducting shell of inner...

I have heard it said that although the temperature of space (NEO) is very cold, the vacuum is actually an insulator and therefore satellites have problems overheating. This is the reason given that spy satellites cannot be painted black, and therefore be made harder to see. However, in the...

Dear all, I have been thinking, if insulators have their valence band filled, then which band does the extra electrons go when it is negatively charged?? If it is the conduction band, then it would become a conductor... Similarly, if it is positively charged, there would be a hold in the...

Hi, Does anyone know which insulator will have very high dielectric strength at room temperature? The dielectric strength is the electric filed strength of a material can resist before it breakdown.

To put a uniform charge on the surface of a conducting hollow sphere one just needs to touch it at one point with an electrode. To put a uniform charge on the surface of an insulating hollow sphere, do you have to somehow physically spray charge all over it?

Homework Statement We have a solid cylinder of radius R0, and it has a uniform charge density p. The length is much greater than its radius, so it appears almost infinite. Homework Equations Find the electric field inside the cylinder where r<R0 and outside the cylinder where r>R0...

Potential of Concentric Spherical Insulator and Conductor...Please Help Homework Statement A solid insulating sphere of radius a = 4.9 cm is fixed at the origin of a co-ordinate system as shown. The sphere is uniformly charged with a charge density ρ = -108 μC/m3. Concentric with the sphere...

Potential of Concentric Cylindrical Insulator and Conducting Shell...Please Help Homework Statement An infinitely long solid insulating cylinder of radius a = 3.6 cm is positioned with its symmetry axis along the z-axis as shown. The cylinder is uniformly charged with a charge density ρ =...

When a dielectric material insert between two plate capacitors the conductivity may increase. Normally we talk that a dielectric is insulator?but how can it increases conductivity?

glass as an insulator? i have lately done some reading on the properties of glass and have seen threads where some say glass is an insulator and others say it isn't. what is the real fact about the thermal conductivity of normal glass, e.g. the wine glass or the glass beaker. are they really...

When a charged body is brought near an insulator, the side facing it acquires a charge of opposite sign because of induction. Is it possible for an insulator to acquire same charge as charged body? (by induction, touching or any other means)

Hi, I've got an applications where I need an insulating washer/disk in order to insulate stainless from stainless at 50 degrees Kelvin. I need help in selecting a material to do the job. I.e. low thermal conductivity, durable enough at 50 K to take a compressive static load of approx 40...

Homework Statement Expalin how a positively charged insulating rod can be used to give a metal sphere a positive charge. Cam the same rod be used to simultaneously give one sphere a psotive charge and another sphere a negative charge without the rod having to be recharged ?? Homework...

I am working on a research project in which i need to create a uniform electric field inside of a tube. I am using a glass tube and wrapping copper tape rings on the outside of the tube. The copper tape is charged to create an electric field. My question is whether or not the field will be...

Homework Statement A long cylindrical insulator has a uniform charge density of 1.79 µC/m and a radius of 3 cm. What is the electric field inside the insultor at a distance of (a) 2 cm? [Answer in units of N/C] (b) 10 cm. Homework Equations ∫ E • dA = Q_enclosed / e_0The Attempt at a Solution...

I feel so ashamed to ask a question this simple, but how does an insulator get charged? Let's say rubbing a glass rod with cat's fur. I thought that insulator means there is no free electron. Does rubbing means turning the neutral atoms at the surface of the glass rod into ions? or...

Higher dielectric constant means better insulator. Water has a dielectric constant of 8, which is enormous(according to Walter Lewin), but it still is a very good conductor of electricity, why?

i do not really understand wigmer-mermin theorem in my impression, it states that there is no continuous symmetry breaking in 1d and 2d so does wigner-mermin theorem rules out SF-Mott insulator transtion in 1d and 2d lattices ?