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Questions tagged [conductors]

For questions about materials which allow the flow of an electric charge (electrical conductors) or the transfer of heat (thermal conductors) through them.

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1answer
434 views

Difference between dielectric and insulators

AS per my knowledge - dielectric are insulators which can be polarized in presence of external electric field. Does that mean all Insulators are not dielectrics ? If yes then kindly share example of ...
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2answers
2k views

Electric Field “at” the surface of a conductor

It has been pointed out to me that the Electric field exactly on the surface of the conductor is conventionally taken to be $E=\frac{\sigma}{2\epsilon_0}$; does this come from taking the midpoint of ...
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1answer
86 views

Conductor completely surrounds another conductor

A problem in my book asks to "Demonstrate that the capacitance of any conductor is always smaller than or equal to the capacitance of a conductor which can completely surround it". The solution to ...
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1answer
2k views

Energy Loss during Sharing of Charge between two Capacitors

It is fairly easy to show that there is always a loss energy when two capacitors share their charge to attain the same common potential, but is it with the same ease that one can explain why it ...
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1answer
81 views

Skin Effect Explanation

I do not understand some things about the Skin Effect. Its Wikipedia definition is: Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor ...
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1answer
145 views

Why Electrical conductivity tensor is symmetric? Or is it not always symmetric?

How to show that the electrical conductivity tensor is symmetric? (or it's not always symmetric?)
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3answers
156 views

How to show that the electrons responsible for a current have an energy within $k_BT$ of the Fermi energy?

It is commonly written in textbooks that in metals the electrons responsible for an electric current are the ones that have an energy about $E_F$ and a few $k_BT$ around that energy. See for example ...
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2answers
67 views

Is it possible to become electrocuted even if using a Faraday suit on a high-voltage line?

I am a writer. I'm working on a novel (yes, fiction) but want to do my best to present a passage as accurately as possible. The crux of the question is whether or not someone using a Faraday suit ...
2
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1answer
38 views

Is there an magnetic field around ideal conductor?

Im gonna dive straight to the point: If you run some current through, say, copper wire you will get a magnetic field around it; that is how the gauss guns work. My questions are: 1) Is it possible ...
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1answer
362 views

Reason for gold being the most malleable and ductile of metals

I understand how fcc structure enables plastic deformation in metals, but why is gold, in particular, the most malleable and ductile of fcc metals? Is there something about the electronic structure ...
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2answers
197 views

Why is the assumption of spheres being point charges invalid for small separations?

I have a hollow charged sphere and I am measuring the force between it and a grounded metal plate. How does the assumption that they are point charges (using method of image charges) become invalid ...
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2answers
2k views

Difference between conduction current density & convection current density?

Could anyone please explain the difference between the conduction current density $J=σE$ and the convection current density $J=ρv$? I really appreciate any examples or applications to further ...
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2answers
272 views

What will happen to the charges if we dig a hole in a hollow charged conductor(example a hollow conducting sphere)?

I am confused about how will the charges on outer surface of a hollow charged conductor would distribute themselves to make electric field zero inside after we dig a hole in the hollow conductor going ...
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2answers
398 views

Electric field near a conducting surface

while calculating electric field near the surface of a conductor,we take only a small patch of charges near the point and draw a Gaussian surface in the form of a cylinder to calculate the field,i do ...
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3answers
679 views

Net electric field inside a conductor

I was reading Electrostatics, and I came across this statement which said that the electric field intensity inside a conductor is zero under electrostatic conditions. Let's take a solid conductor, so ...
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3answers
3k views

How is the electric field created by a battery inside a conducting wire constant?

My book says that a cell (or a battery) creates a constant electric field inside a conducting wire. They've made use of a cylindrical conductor for the purpose of explanation and said that since the ...
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3answers
2k views

What is “surface potential” of a conductor?

If there exists a charged conductor, the surface has a potential. This potential at a point on the surface is created by the charge distribution of all the other points on the surface. This means that ...
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1answer
226 views

Can't see any difference between Dirichlet and Neumann boundary conditions on the surface of a perfect conductor?

If we consider the Helmholtz equation for electromagnetic wave propagation and let $\partial \Omega$ be the surface of a perfect conductor with Dirichlet boundary conditions, ie. $u(x) = 0$ for $x \in ...
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3answers
12k views

Why is silver the best conductor of electricity?

I've been wondering why silver is the best conductor of electricity for a while now, and I've observed that in Group 11 transition metals where silver is located, copper and gold too are also one the ...
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1answer
530 views

Removing an electron from a conductor

I'm trying to understand how to think of and visualize a conductor where charge is added. As I understand, conductor are defined as materials (where the nucleus is stationary) that permit electrons ...
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1answer
1k views

Refraction of the electric field lines, at the interface of separation between two conductive media

Suppose we have 2 media with electrical parameters ${\varepsilon _1},\,{\sigma _1}$, respectively ${\varepsilon _2},\,{\sigma _2}$, separated by the plane surface $\Sigma $; electrical charge surface ...
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2answers
703 views

Symmetries of non-parallel infinite conducting planes

Suppose I have semi-infinite conducting planes that intersect at some angle $\theta_0$ and have a potential difference of $V$ (the axis of intersection is somehow insulated so they are not actually in ...
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3answers
901 views

Field due to induced charges in and out of a conductor with a cavity that contains a charge inside

I want to know the proof for the following statement:- The net electric field due to the "induced charges on the surface of the cavity and the charge inside the cavity" is zero everywhere outside ...
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1answer
152 views

What do the batteries actually do to the electrons?

I am plagued by this simple question that what force exactly causes the motion of an electron in the middle of a lattice of electrons of a wire? a. Is it an electric field created inside a wire due to ...
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1answer
158 views

Gauss law and electrostatic induction. Concentric spheres

Imagine you have hollow concentric spheres A and B with radius a and b (b>a), respectively. If A is a conductor and B has a certain density charge, I´ve been taught that B will induce some net charge ...
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1answer
2k views

Electric field at surface of a spherical shell

The shell theorem provides a well known result that for a spherical shell with uniformly distributed charge $Q$ and radius $R$, the electric field at a distance of $r$ from the center is: $$\begin{...
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3answers
751 views

How can a parallel circuit work? [duplicate]

The electrons always takes the easiest way in a circuit, right? So in a parallel circuit, why does the electrons flow through all parts of the circuit and not just the one with the least resistance?
2
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1answer
300 views

Semiconductors, Solid-State Physics

We know, that conductors, conduct because their valence energy band is "half" full, and k ("wave vector") can increase and therefore the electrons under the influence of a electric field can "move", ...
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3answers
786 views

How does a conductor shield the outside from its inside?

If I have a charge of $+q$ placed arbitrarily within the spherical conducting shell, by Gauss' law, the $E$ field produced will be created outside the shell, as if the charge were placed at the center....
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1answer
603 views

Are the conducting electrons in a metal counted as free or bound charges?

Caused by another question on the propagation of EM waves in a metal, I got a bit confused on the notion of free and bound charges in a metal (sometimes called induced or external). Are the free ...
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2answers
1k views

Charge distribution on a Gaussian surface

In the text, it is said that the skewed distribution of positive charge on the inner wall cannot produce an eletric field in the shell to affect the distribution of charge on the outer wall. Why? ...
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2answers
358 views

Will two touching, neutral conductors in an electric field separate?

If you put two square, neutral conductors in the middle of a uniform electric field such that they are touching, will they separate? I thought yes. When they are touching, as shown in the picture, I ...
2
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1answer
267 views

Magnetic Field in the presence of a conductor

I am studying for my quals and came across an old question that reads like the following: There are two regions in space separated by an infinite conducting plane. Region 1 has a magnetic dipole ...
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1answer
1k views

Electric Field-Drift Velocity

Why is the net velocity of electrons (drift velocity) considered to be zero, before setting up any electric field? I mean in the derivation of the equation drift velocity: $$ v =-\frac{Eet}{m} $$
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3answers
90 views

Measurements from inside conductors

We have known for some time now that when electric field is applied across any conducting shell, then electric field inside it would be zero. It also has some fantastic applications such as ...
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0answers
51 views

what is the current operator of an interacting electron gas?

If i have an electron gas with coulomb interactions, what would be the current, operator. I would write the Heisenberg equation of motion for the density operator, than write the continuity equation ...
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0answers
34 views

Two conductors in free space [closed]

In free space there are two masses: Metallic sphere of mass $M$, radius $R$ and total charge equal to 0. It has also a resistivity $\rho$. Metallic sphere of mass $m$, radius $r$ and charge $...
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0answers
85 views

Potential near a strip - conformal maps [closed]

I need to solve this problem: An infinitly long wire(at $y=h,x=0$) placed (symmetrically) next to a semi-infinite conducting strip ($y<0$ and $|x|<a/2$). Find the potential in all space. ...
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0answers
1k views

How do excess charges move in an insulator?

I am currently studying intro into electrostatics and reading my notes from teacher that stated, "an insulator holds on tightly to its outer electrons and does not permit the flow of electric charges ...
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0answers
650 views

Tap water conductivity differences between AC and DC

Direct current is often used in electrolysis and because of the alternating nature of AC, it's not great for electrolysis. Tap water, however, conducts AC really well. But why is that? Why does ...
2
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1answer
82 views

Do 2 conductors (1 grounded via resistor) reach equipotential, before surplus electrons drain to earth?

Case I: a negative conductor makes contact with a neutral conductor. Negative donates some electrons to neutral, until there is 0 potential difference. Then they both are slightly negative. This ...
2
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1answer
520 views

Location of mirror charges (method of images)

I was reading about method of images from Griffiths and I was thinking about a situation where a charge is kept inside a spherical cavity of a conducting shell rather than placing it outside a ...
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4answers
825 views

Charged non-conductor [duplicate]

A conductor is defined as it has free electrons to move, but when non conductor attain charge, it would also have free electrons. so it should behave like a conductor or not?
2
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1answer
69 views

Electron emission from insulators?

can electron emission happen from insulators? I mean can the electrons in an insulator jump into the vacuum around them when sufficiently large electric fields are applied like in conductors?
2
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1answer
83 views

Magnetostatics or dynamics?

A spherical conductor, carrying a total charge $Q$, spins uniformly and very rapidly about an axis coinciding with one of its diameters. In the diagrams given below, the equilibrium charge density on ...
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2answers
94 views

Two balls are attached with a very long and thin conducting wire to two conducting plates. How does the capacitor react in this situation?

The question is as follows (taken from a previous exam): Two balls (conductors w/ Radius $R_1$ for left ball ball, $R_2$ for right) are attached with a very long and thin conducting wire to two ...
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0answers
124 views

Van der pauw method for an isolated hole

Van der pauw method is a way to measure the resistivity of a material with arbitrary shape while it meets some specifications ( being homogeneous and ...). One of the conditions is that the sample ...
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1answer
1k views

Why charge distribution is greatest at pointy edges of a surface? [duplicate]

If we have a conductor which is in electrostatic equilibrium, then the charge distribution over this surface $\sigma$ is greatest at the sharp edges of that surface. Why is this the case? I want ...
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0answers
270 views

Electric field in a “concave” conductor

I am aware that the electrons are distributed across charged conductor surface so that the areas with smaller radius of curvature have more charge per surface area. But what happens when the ...
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0answers
69 views

Earth as a conductor and emf produced? [closed]

Since about 73% of total surface of Earth is occupied by water, its internal is also occupied largely by hot molten mass.Let,the whole earth is considered a conductor.Sun is a source of gravitational ...