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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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How far do electrons actually move along a conductor under an alternating current?

This is more or less a curiosity question. But I have had really good luck with stack exchange so far. If I can expand on my question a little bit - it may not be super important, but I know under say ...
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Electric field in dielectric sphere surrounded by conductive shell connected to ground? [on hold]

Electric field in dielectric sphere surrounded by conductive shell connected to ground? The radius of the dielectric sphere is $a$, while the radius of the conductive shell is $a$ (internal surface) ...
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2answers
40 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 ...
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3answers
78 views

Do real electrons solve the Thomson Problem?

The question of how $N$ electrons (seen as point charges) on a conducting sphere will arrange themselves in the electrostatic final state was first posed by J.J. Thomson in 1904--hence, aka the ...
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52 views

Non-ohmic conductors

Non ohmic conductors are said to be the conductors that do not obey Ohm's Law. The V-I graph for them is not a straight line unlike ideal ohmic conductors. According to me Ohm's Law states: The ...
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2answers
61 views

Charge Distribution on a perfectly conducting hollow shell

As shown in the figure, I have a hollow shell which contains a charge at its centre and another charge is placed outside the shell (some distance apart). I know that the situation this figure depicts ...
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13 views

Why is there an accumulation of charges at the junction of 2 rods of different metals joined together?

Let two similar rods of different metals ( say copper and iron ) are joined together and some current is let to flow . Is there a charge accumulation at the junction? 1. If so what is the cause of it ...
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44 views

Paradox in conservation of energy

Let us assume there is a constant electric field in an interested region (finite volume)and a non-conducting object is thrown into it with speed $v$ and now take the second scenario with the same ...
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1answer
29 views

How to compute the self-capacitance of a conductive shape?

(Depending on the answers given, this question might be better suited for Math.SE, but I don't think so.) I recently learnt about the notion of self-capacitance of a conductive shape, which now seems ...
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1answer
34 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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30 views

Capacitance of spherical capacitor when inner sphere is earthed

Consider the following derivation: (Source: http://www.ncert.nic.in/html/learning_basket/electricity/electricity/electrostatics/inner_sphere.htm) If a charge of $+Q$ coulombs is given to the outer ...
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Metal rod in an electric field

A metallic rod is placed in a uniform electric field. Why is an electric field induced in the opposite direction?
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62 views

Is it the current which create magnetic field, or vice versa, or both?

Talking about stationary magnetic field, it is said that if a conductor rotates inside the field, a current is induced. Also, I read that current (moving charges) generate magnetic field, too. How are ...
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1answer
42 views

On the electric field created by a conductor

The electric field created by a conductor at a point $M$ extremely close to it is $\vec{E}=\vec{E_1}+\vec{E_2}$ where $\vec{E_1}$ is the electric field created by such a tiny bit of the conductor that ...
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1answer
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How do I solve for the voltage on a geometry that has varying thickness of a conductive metal?

I currently have a 3D geometry which is made from an isotropic material. In my case this material is simply a highly conductive metal. We can think of this geometry almost as a thin film with slightly ...
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1answer
57 views

Relative Permittivity in a “Good Conductor”

I have a question in which I need to show that sea water is effectively a "good conductor", when considering the propagation of radio waves of frequency $< 10^9$. We're given that the conductivity ...
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2answers
53 views

What is the voltage in electrical circuits?

I understand what the voltage is and I realize that the battery makes an electric field due to the accumulation of the charges in the anode and cathode this electric field causes electric potential ...
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1answer
40 views

Why does charge 'stick' to the Gaussian surface?

I'm currently studying Gauss's Law and interaction of the charge with different Gaussian surfaces etc. But here's something that I couldn't understand. Why does a charge 'stick' to a Gaussian surface? ...
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1answer
57 views

How is the $E$-field getting canceled between outer and inner surface of a neutral conducting spherical shell?

I am reading Purcell's E&M book and in one of the example questions, it shows that there is no E field between outer and inner surface after a a point charge is located at an arbitrary position ...
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3answers
172 views

Electric field due to uniformly charged infinite plane sheet

For getting the electric field in this case we use the Gauss's law. we get the equation $$ 2EA = pA/\epsilon_0 $$ here $E$ is electric field, $A$ is the cross sectional area, $p$ is the uniform ...
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1answer
79 views

Point charge inside hollow conducting sphere [closed]

Above there is a 2D pic of this problem. $S$ is a conducting sphere with no charge. I am considering the electrostatics case. It is a hollow sphere: inside its cavity lies a point charge $q$,...
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1answer
30 views

How do I experimentally measure the resistance from using dielectric grease on battery posts?

The internet gives lots of contradicting advise about greasing or not greasing car battery posts to prevent corrosion. So rather than rely on the internet, I want to perform an experiment so that I ...
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1answer
82 views

Proof that $\vec{E}$-field is constant inside cylindrical resistor

I am reading a proof that the $\vec{E}$-field is constant inside a cylindrical resistor, and I don't understand one of the steps. It is stated that since the surrounding medium is non-conductive the ...
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1answer
78 views

Charge accumulation in wire

I came across a question about charge accumulation. It states that if a steady current flows in a wire composed of a copper and iron wire of same area (see fig), will the charge accumulate on the ...
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0answers
36 views

Gauss's Law about excess charge on conductors, quantum mechanics, and doped semi-conductors [closed]

Does quantum mechanics predict that there is any probability of finding excess charge inside a conductor? I've read an explanation about the distribution of excess charge placed on conductors. The ...
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2answers
66 views

How does the current become homogeneous within a circuit?

I have two questions: In a given circuit with resistances of different values connected in parallel, there is a different build up of electrons when the power source is turned on. Then, how is the ...
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2answers
77 views

Charge distribution in the wires and resistor, in a DC circuit

1) How do the electrons in a wire with 0 or negligible resistance arrange themselves in order to make the field in the wire 0? 2) The electric potential drop across a resistor is far more than ...
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0answers
13 views

How is the charge density on the surface of a PEC wedge $\rho=- \frac{\nu C_2\varepsilon_0}{r^{1-\nu}}$ given by the electric and magnetic fields?

For a perfectly conducting wedge the components $E_z/H_z$ (parallel) and $E_t/H_z$ (tangential) of the electrical and magnetic fields are given by \begin{align} E_z & = j\omega \mu_0 C_1 r^v (\nu \...
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1answer
30 views

Does “charge density” account for all charges, or only negative charges, and do opposite charges cancel each other or add?

if I had 10 electrons and 8 protons in a meter cubed would the charge density be 2 or 10 or 18? I suspect 10, but I don't see why charge density only takes into account the negative charges. another ...
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1answer
46 views

Coaxial cable with compound dielectric

I'm trying to solve a problem from Reitz and Milford's Foundations of Electromagnetic Theory (3rd ed, problem 4-8), and don't know how to start: A coaxial cable of circular cross section has a ...
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1answer
36 views

Do charges in a metal group up a little in the middle?

Around the edges of a metal, the density of electrons is higher than the rest of the metal. I think this is because every electron is surrounded by neighbours pushing them away but once you get to the ...
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0answers
40 views

Partial capacitances of a system of conductors - conductor acting as a shield

I have a small question about the following problem. The figure represents the cross-section of a three-conductor system comprising a communications coaxial cable of length l running parallel to a ...
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1answer
37 views

Showing that the exterior surface charge density of two parallel plates with thickness are equal

I have some problems with the next exercise. It states: Two infinite conducting parallel plates I and II, with thickness $t_1$ and $t_2$ respectively are separated by a distance $L$ from its nearer ...
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1answer
54 views

Creation of electric field inside a conductor

My book says that as soon as the two ends of a conducting wire touches the two terminals of a battery, it generates an electric field inside the conductor. Why?
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1answer
59 views

Difference between bound and free charge/current in a perfect conductor

For the case of charge, it seems clear that in a perfect conductor the free charge refers to the excess charge that has been dumped into the conductor, while the bound charge refers to the charge that ...
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4answers
144 views

Can a positively charged conductor have negative surface charge density somewhere?

This is a simple question that occurred to me while thinking about electrostatics. Let's consider a positively charged isolated conductor in equilibrium. In general, the surface charge density varies ...
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2answers
35 views

Magnetic force between two long conductive wires with current

I was asked to calculate the total magnetic force between two long conductive wires with current on them, flowing in the same direction. I used the formula F$_1$=$μ_o\frac {I_1I_2l}{2πd}$ and got a ...
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1answer
31 views

Direction of magnetic field lines around a conducting wire

By way of the first uploaded picture I was taught that magnetic field-lines around a long conducting wire with a current are shaped like concentric circles around the wire. However, a few pages ...
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1answer
47 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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125 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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1answer
81 views

What happens to potential when a charged body is placed next to an uncharged conductor?

I know that the potential of the charged body decreases due to induction however I feel as though I need a more in depth answer. Why does induction cause the potential of the charged body to decrease ...
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1answer
44 views

derivative of the electric field along the normal to the surface near the conductor

how to derive the formula approves the derivative of the electric field along the normal to the surface near the conductor is inversely proportional to the principal radii of curvature? $\frac{\...
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2answers
69 views

What actually happens during metallic conduction?

My book mentions that when an electric field is applied to a conductor the electrons get accelerated in a direction opposite to that of the field. These electrons however collide with the atoms on the ...
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2answers
39 views

Does electric current create positive ions while flowing through a conductor?

As the conduction electrons are free to move randomly, i.e they are not restricted to a particular atom, then why don't these atoms get positive charge due to loss of these conduction electrons?
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4answers
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Question on direction of electric field

My physics textbook (1st year university course on Electrostatics) mentions that when looking at a positively charged metal disc from the side, the electric field is located perpendicular to the ...
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3answers
114 views

Electric shielding skin depth

I read that lower the frequency,the deeper is the skin depth in conductor.If we are using piece of thin conductor,like aluminum foil for example to shield something from electric fields,it would ...
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1answer
43 views

Why there is no charge within the conductor even if the charges are static?

"When excess charge is placed on a solid conductor and is at rest, it resides entirely on the surface, not in the interior of the material. �" Source: University physics 13th edition p(736). ...
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0answers
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Eletric potential outside a conductor sphere [closed]

During my chemistry graduation, my Physics III professor gave to us an exercise that would worth an adition in the final mean. Well, I've finished the graduation, and the exercise was forgoten until ...
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1answer
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What happens if I place a charge inside a hollow conductor and fix it? [duplicate]

So I know that when you put some charge inside a counter, it resides uniformly on the surface of the conductor in order to make the electric field zero everywhere inside the conductor.. But what if I ...
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0answers
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Skin effect fully explained by plane wave attenuation?

I went over the explanations of the skin effect in multiple sources. However, I still don't understand how the fact that this equation: \begin{equation} (\Delta - \mu_0\sigma\partial_t - \frac{1}{c^2}...