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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40 views

Confusion regarding solution of a problem of conducting spheres

Two conducting spheres of radii $r_1$ and $r_2$ are connected by a metallic spring of stiffness $k$ and natural length $ l \gg r_1, r_2$. A positive charge $+Q$ is slowly delivered to any sphere. Find ...
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5answers
71 views

How do photons reach thermal equilibrium with the walls of the blackbody cavity?

There's a lot that has been confusing to me about Planck's radiation law, and at this point I feel like I've got the hang of most of it. There is really only one last question that I can't resist ...
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3answers
116 views

Why is voltage not affected by wire length even though it is mathematically given as ($V=E\cdot d$), for a wire of length $d$?

If there is $1C$ charge in other side of a battery, the potential being $$V = k\frac{q_1q_2}{r}$$ should change as $r$ changes.
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1answer
14 views

Charge on a conducting sphere

As far as I know, to have a net flex through a closed surface there must be a charge inside it. However, what if I have for example a conducting sphere where the charge accumulate on the surface, will ...
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1answer
53 views

Gauss's Law for planes

Why when we apply Gauss's Law on a conducting plane we choose the Gaussian surface to be a cylinder which one end of it is inside the conductor, whereas when we apply Gauss's Law on an insulating ...
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2answers
53 views

How does earthing happen?

Earthing, as I have been told, is done by inserting a conductor in the ground whilst it is connected to the body whose earthing needs to be done. But how does the charge get transferred into the ...
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1answer
62 views

Is drift velocity of electrons 0 in 0 resistance wire?

In a 0 resistance wire electric field inside the wire is 0 as there is not potential difference . Which means when charges once start to flow ,no external force acts on them and therefore no electric ...
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2answers
25 views

How does a battery bring conductors out of electrostatic condition?

What does a battery exactly do to the conductors (eg metals)? How does it develop a field inside a conductor? On applying external field to the conductors (* I think that there will be a potential ...
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1answer
33 views

Contribution of inner induced charges to the electric field outisde

We have an arbitrary hollow shaped conductor, with small thickness. Suppose we place a charge $q$ at any arbitrary location within the hollow shaped conductor. By Gauss's law there will be a total ...
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0answers
29 views

Why the electric field inside a solid sphere is non-zero according to gauss while we know that the electric field inside a conductor is zero?

We know that the electric field inside a conductor is zero, but in my book, according to Gauss' law, the electric field inside a solid sphere (it's not mentioned if it's a conductor or non-conductor) ...
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1answer
59 views

What exactly causes resistance?

According to Ohm's Law, $V=IR$. Here $R$ denotes the resistance. It's the way I was introduced resistance. The definition is not convincing me. First of all I don't understand what causes resistance? ...
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2answers
51 views

Does superposition principle of electric fields hold for conductors?

Suppose we have two identical oppositely charged spheres separated by some short $ x $ distance, then if we say that superposition principle holds, then at all points in space outside the conductors, ...
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1answer
39 views

How is electric current possible if no electric field exists inside a conductor?

How is electric current possible if no electric field exists inside a conductor? Since no electric field exists inside a conductor. How is electric current possible as $$v_d=\frac{(eE)t}{2m},\;\;{E=0}...
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2answers
77 views

What is the basic physics of current-electricity? [closed]

Why current decreases when length of resistor increases and How the speed of electricity is almost $c$ (speed of light)?
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0answers
20 views

If we take a an ideal conductor and pass a constant electric field through it, what should be the ideal behavior of its free electrons?

When a constant electric field is passed through an ideal conductor, charge separation takes place across the given conductor. This charge separation generates an electric field of its own inside the ...
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0answers
23 views

What is the potential outside a conducting cube with specific plates held at potential $V$?

I have a conducting cube of dimensions $[0,a]\times[0,a]\times[0,a]$. The plates at $z=0$ and $z=a$ are held at potential $\phi(x,y,z=a)=\phi(x,y,z=0) = V$. For the other plates $\phi$ is held at $0$. ...
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0answers
6 views

Doubts about the microscopic derivation of Joule heating for degenerate fermi gases

The typical derivation of Joule heating: power = IV claims that each electron crossing the circuit losses an energy Ve (V=voltage difference, e=electron charge). If this energy is transformed into ...
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1answer
37 views

At what speed does a magnetic field form from the flow of current?

When an electrical current flows through a conductor and produces a magnetic field, does the magnetic field in the conductor form at the drift speed of the electrons in its structure or the velocity ...
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1answer
20 views

Is thermal conductivity in a thin, malleable metal possible or practical without conducting electricity? [closed]

I'm looking to be able to apply and control heat to a malleable metal, ideally a wire. Perfect conditions would be a wire that takes a controlled amount of heat (heated to) between 250-450 degrees, ...
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1answer
36 views

Relevance of conductors being equipotential in the proof of second uniqueness theorem

I am going over the proof of second uniqueness theorem in International 4th Ed of Griffiths Electricity and Magnetism. In page 122, followed till the part where two fields $\vec{E_1}$ and $\vec{E_2}$ ...
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1answer
39 views

Does random motion of electrons take place in 0-resistance wire?

In nodal analysis we often assume a wire to have 0 resistance and hence we assume that its ends have the same potential. As the potential difference across the ends of the wire is 0, there is no ...
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1answer
35 views

Induced Charge on Conducting Surface

I am making my way through Griffiths' Introduction to Electrodynamics and ran across the following passage: Suppose a point charge $q$ is held a distance $d$ above an infinite grounded conducting ...
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1answer
32 views

Can a conductor act as a battery?

If a conductor is kept in an external electric field then it develops charge separation and counters the external field. If we connect its opposite ends using a wire and a load then can it act as a ...
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2answers
42 views

$\int_C\limits{\vec E}\cdot{d \vec r}$ inside and outside a perfect conductor with an intriguing result

Consider a solid conductor of any arbitrary shape and with charges lying on its surface. Therefore, the electric field is zero inside but nonzero outside. Now consider two points, P and Q, on the ...
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1answer
30 views

How electric field changes on changing area of wire?

I know that in an isolated conductor when an external field is applied the charges rearrange themselves end field inside conductor becomes zero. But when this conductor is connected to a battery then ...
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4answers
105 views

Electric field inside a conductor non zero

I have a spherical conductor with a charge $+q$ place inside the cavity, now the charges redistribute as shown, If I apply gauss law where my guassian surface is such the $q$ inside is non zero now , $...
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0answers
6 views

Induced voltage on a third conductor due to the field of a capacitor

I just started solving PDE solvers for electrostatic problems using MATLAB, which solves for scalar unknown fields. I know how to set up Dirichlet and Neumann boundary conditions, and have produced ...
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1answer
49 views

Electrostatic Potential, Potential Energy, Method of Images [closed]

I am a beginner in problem solving in the field of electrostatics. Well equipped with basic strategies and use of gauss' law. I wanted to analyze the situation below and couldn't wrap my head around (...
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0answers
70 views

How to derive this equation (it has cross products)?

I have an equation (Eq 10) given in this article $$ \mathbf{\sigma}= \frac{1}{V}\sum_{n,\vec k} \mathbf{J_{n,\vec k}^s}\times \mathbf{J_{n,\vec k}} \bigg(-\frac{\partial f_{n,\vec k}}{\partial \...
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0answers
28 views

Band theory Splitting of levels

In the band theory of solids, when various energy levels create bands which levels are these.? For example for a single Copper this is how electrons are packed: 1s2 2s2 2p6 3s2 3p6 3d10 4s1. So when ...
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0answers
24 views

Are there any viable replacements for Indium-Tin Oxide electrodes?

I am looking to obtain a metal oxide ceramic that can be synthesized from a Sol-Gel procedure that is both conductive and flexible. Indium-Tin oxide does apply in this case, however the cost of Indium,...
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5answers
120 views

Why is the electric field inside a conductor zero at every point?

There are a couple of arguments on how the electric field inside a conductor is zero. Some of them appear to me to be unreasonable; I will explain. Let's consider a charged conducting sphere. I ...
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3answers
59 views

Why Does Resistance of a Conductor Increase With Length?

Most common explanation is as wire is longer electrons experience more collisions as they move from one to the other end of the wire. While I agree with this what I don't understand is that for DC, ...
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1answer
39 views

Electric Field due to charges inside cavity

Imagine a conducting body as shown: A positive charge +q is placed inside the cavity of the body. Now due to induction a negative induced charge -q has appeared on inside surface of cavity. Is the ...
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1answer
60 views

Proof of electric field intensity due to an infinite conducting sheet

I am reading the proof of electric field due to large uniformly charged sheet. It is give as Consider an elemental strip of width $dx$ at a distance $x$ from point $O$. The linear charge density $\...
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0answers
11 views

Potential drop across a wire with zero resistance [duplicate]

I am currently studying Circuits and it is written in my book that the Potential Drop across a wire with zero resistance is 0. If there is no potential drop then why do electrons flow through the wire ...
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0answers
23 views

Can we distinguish semiconductors, metals and Insulators from Kronig-Penney model?

Can we distinguish semiconductors, metals and Insulators from Kronig-Penney model? Is it only for metals? If we draw the E vs K diagram using the kronig-penney model why energy bands are increasing as ...
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1answer
61 views

Does the shape of a wire affect the electric current in it in any way?

Say we have a straight wire connected across two terminals carrying electricity between them. If everything is kept the same (voltage across the two terminals, resistance of the wire, etc.) will there ...
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1answer
31 views

Electric potential of a circuit (potential difference to be exact)

Electric potential in a space as like as gravity is something understandable but when it comes to circuit I always get puzzled about this. I am looking for help regarding this topic. Is electric ...
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0answers
29 views

Can the direction of electric field in a parallel plate capacitor be tangent to the surface of the plates?

We have two parallel plates connected to a source of emf E, and let's say we introduce a dielectric of constant K, (assume a dielectric slab for simplicity), and we are free to vary the length of ...
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0answers
17 views

Potential distribution between metal plate on ground and a buried spherical electrode

The problem described in the picture is, that a current flows through a wire to the shallow buried spherical grounder and a metal plate with radius R is on floating potential, it's conductivity is ...
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1answer
31 views

Why don't charges leak through conductors?

Imagine a negatively charged conducting sphere placed in vacuum. Now all the negative charge must be at the surface. Any electron present at the surface of conductor will experience a net repulsive ...
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2answers
53 views

Mathematical proof of charging by induction

If we bring a positive charge +Q near a neutral conductor , we know that the surface near the source gets-Q and opposite to it gets +Q, but why do these induced charges have to be equal in magnitude ...
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3answers
254 views

If an electron is repelled by another electron how is it that we get an electric current?

As we know that an electric current is a flow of electric charge in a circuit, and in electric circuits, the charge carriers are often electrons moving through a wire. Now, since we know that like ...
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0answers
44 views

Phase difference between electric and magnetic fields of EM wave in a conductor?

When an EM wave travels incide a conductor , we see that there is a phase difference between the Electric and magnetic fields within the conductor. The magnetic field lags behind the E field and this ...
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1answer
21 views

Current flowing in a circuit made up of ideal conducting wires

Taking a simple circuit with a battery to provide a potential difference and some resistance across, also our circuit is made up of an ideal conducting material so $\sigma$ is infinity. Now I have ...
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0answers
71 views

Conductor with two cavities

I am going through the last example discussed in this site which discusses a conductor having charge in two cavities inside as given by the following set up: The only rule obeyed is that when the ...
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2answers
85 views

Is Electric potential constant inside a conductor in all conditions?

As electric field remains the zero inside the conductor so the potential at the surface should be the same as inside, but i came with a situation which is as follows: if a spherical conductor is ...
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2answers
75 views

Do holes flow in a conductor? [closed]

I want to if holes flow in a conductor and, if yes, why. What happens when holes reach the end of the semiconductor?
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1answer
51 views

Why any electric field doesn't exist outside the conductive spherical shell?

The conductive spherical shell(green one) and the conductive sphere are given(blue one). The inner sphere is charged with $Q~$ and the outer shell is grounded and not charged. $V_{\text{a}}:=\text{...

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