In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electrical current) in one or more directions. Materials made of metal are common electrical conductors. Electrical current is generated by the flow of negatively charged electrons, positively charged holes, and positive or negative ions in some cases.
In order for current to flow within a closed electrical circuit, it is not necessary for one charged particle to travel from the component producing the current (the current source) to those consuming it (the loads). Instead, the charged particle simply needs to nudge its neighbor a finite amount, who will nudge its neighbor, and on and on until a particle is nudged into the consumer, thus powering it. Essentially what is occurring is a long chain of momentum transfer between mobile charge carriers; the Drude model of conduction describes this process more rigorously. This momentum transfer model makes metal an ideal choice for a conductor; metals, characteristically, possess a delocalized sea of electrons which gives the electrons enough mobility to collide and thus affect a momentum transfer.
As discussed above, electrons are the primary mover in metals; however, other devices such as the cationic electrolyte(s) of a battery, or the mobile protons of the proton conductor of a fuel cell rely on positive charge carriers. Insulators are non-conducting materials with few mobile charges that support only insignificant electric currents.
I saw this and thought it was interesting. If one can get beyond the pretentious music, super annoying robotic narration and ignore the completely off the wall theory discussion there remains a reasonably well documented experiment. The measurement shows the B field about a conducting cylinder...
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A flat capacitor formed by two square plates of side 0.3 m which are 2 mm apart. Source keeps voltage 250 V on the plates. What current flows between the plates and the source if the condenser is immersing in kerosene at velocity of 5 mm / s? The relative permittivity of...
I am trying to find the electric field of a hollow, open-ended, thin-walled cylindrical conductor.
I am trying to solve something regarding LINACs:
Assume we have an isolated, hollow, open-ended, thin-walled cylindrical conductor, with a net charge.
The net electric field within the...
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The figure shows a cross section across a diameter of a long cylindrical conductor of radius a = 2.92 cm carrying uniform current 151 A. What is the magnitude of the current's magnetic field at the center of the conductor?
Homework Equations
Biot-Savart's Law
The Attempt...
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Homework Equations
no equations required
The Attempt at a Solution
can someone please verify if my answer is correct. Thanks!
I used the right-hand rule for the motor principle (although another tutor on physics forum told me that its supposed to be the 'left-hand rule'...
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A 0.393 m long metal bar is pulled to the left by an applied force F. The bar rides on a parallel metal rails connected through a 42.9 ohm resistor as shown in the figure. So the apparatus makes a complete circuit. You can ignore the resistance of the bars and the rails...
Hi,
I would like to know how to get the potential difference due to a constant local magnetic field acting on a wire moving at a constant speed perpendicular to the field. What is the link between F = q v ∧ B and the actual difference of potential in the circuit ? How to determine the induced...
A conductor with a large high frequency AC current causes a "Skin Effect" meaning that most of the current flows at the surface of the conductor.
What does the skin effect look like if you have a conductor with one side flattened?
And what does the resulting magnetic field look like?
See...
If you drop a permanent magnet like steel through a copper tube it induces an emf, this is because you have a change in magnetic field/flux? But how? Why? The copper isn't producing a current before the magnet is dropped into it... Does something happen with the electrons in the copper?
Suppose there is a metal disk with an initial excess of charge represented by the four red electrons. Naturally, they reach their equilibrium position on the surface. After this, a new electron (the green one) is added exactly at the center. The repelling forces from the red charges cancel each...
We assume that there is no electric field inside the perfect conductor because relaxation time of metal
is very short.
whereas
J=sigma*E
But if this is the case, how can current flow inside the metal?
-Is this because of battery? If there is a battery connected to a metal...
I just had a test question in my E&M class that asked what would happen to a conductor when placed in an external electric field. One of the "correct" answers was that all of the free electrons would move to the surface of the conductor. I understand that the free electrons would rearrange...
Homework Statement
A conductor 7.5m long, is moved at a uniform speed at right angle to its length and to a uniform magnetic field. The density of the magnetic field is 0.64T. The emf generated in the conductor is 36V and the conductor is part of the closed circuit that has a resistance of...
Hi! I have to build a capacitor out of the following materials: 10 square feet of aluminum foil, 10 square feet of saran wrap (polyvinyl chloride), several sheets of paper, and tape to put it all together. I will only have about 30 minutes to manufacture my design. I have been researching...
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Hey guys, I'm having trouble with a question covering magnectic field on a cilindrical conductor with a cilindrical cavity, here's the question:
Consider a long cilindrical conductor with radius R1, with a cilindric cavity with radius a, in which R1>a. The axis of both...
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EM wave with circular polarization travels in directon z interferes with perfect conducting surface xy.
1. find reflected wave
2. calculate induced charge density and surface current induced on conducting surface
Can you verify if I started point 1. correctly, and give...
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An infinitely long, cylindrical, conducting shell of inner radius b and outer radius c has a total charge Q. A line of uniform charge distribution Λ is placed along the axis of the shell. Using Gauss's Law and justifying each step, determine. A) The Electric Field for r>a...
Hello,
If we have a solid conductor with all of its charge on its surface, and we then enclose some its charge with a gaussian surface that goes inside the solid conductor, will the part of the gaussian surface within the conductor have any electric flux? My textbook says it will have zero...
If a negatively charged Styrofoam plate is brought towards pieces of paper placed on an insulator (ex. a piece of paper), attraction occurs. Repulsion occurs if pieces of aluminum foil, which is a conductor, are placed on an insulator. What would occur if the pieces of paper and aluminum foil...
Why is the electric field just outside a conductor twice the field produced by a uniform sheet of charge?
My textbook's explanation is that you can imagine that near a point P, the charge at the surface of a conductor looks like a small uniformly charged disk centered at P, giving an electric...
A constant voltage V is applied at the two ends of a cable which is a perfect conductor (e.g. a superconductor). Since the cable, anyway, has a non zero inductance L, the current inside it is not infinite but it is proportional to time t: i(t) = V/L * t.
In this situation, how much it is the...
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If the diameter of a wire (conductor) is dimidiated , then its resistance:
A Remains unchangable
B is diminiated
C Becomes two times greater
D Becomes 4 times greater
Homework Equations
R=constant*length/Surface
The Attempt at a Solution
Cross sectional area=pi r^2=pi...
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The resistance of a wire (conductor) in cylindrical form is:
A Disproportional with the length of the wire (conductor)
B Disproportional with the square of the wire (conductor) section
C Proportional with the square of the length of the wire (conductor)
D Proportional with...
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A cylindrical conductor with a circular cross section has a radius a and a resistivity ρ and carries a constant current I. What is the flow of energy into the volume occupied by a length l of the conductor? Discuss why the energy dissipated in a current carrying conductor, due...
I have read this chapter about calculating internal and external inductance of a straight wire here.
http://nptel.ac.in/courses/Webcourse-contents/IIT-KANPUR/power-system/chapter_1/1_4.html
Seeing the flux linked with the conductor itself, emf due to that flux induced in upper half and lower...
bear with me, i know that this question has been asked many time , but i would like a definite answer, now, starting off the external charge density on the outer surface of sphere WILL be uniform by unique solution of Laplace equation and letting the sphere be huge, so, electric field due to...
I was reading through my College Physics text, and it talked about how NASA once swung a 20km long conductor through the Earth's magnetic field and setup a 3500V potential difference along the wire.
I understand that there's no conventional current in that wire, it's not a circuit. But for a...
If you have two independent circuits, and then connect them at two points that are at arbitrary voltages by a single conductor, what happens to the system? A moment after the connection happens, I would assume there to be no current between the circuits since the two circuits would try and...
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Determine the thermodynamic restrictions for a rigid heat conductor defined by the constitutive equations:
\DeclareMathOperator{\grad}{grad}\psi = \hat{\psi}\left(\theta,\grad \theta, \grad \grad \theta\right) \\
\eta = \hat{\eta}\left(\theta,\grad \theta, \grad \grad...
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"Demonstrate that the capacitance of a conductor is always smaller than or equal to that of a conductor which completely surrounds it."
2. Homework Equations /3. The Attempt at a Solution
Solving this problem for concentric spherical conductors is easy enough, but I...
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Homework Equations /The Attempt at a Solution[/B]
I am trying to solve problem 2-13 from my textbook "Principles of Electrodynamics" (see image below).
I believe that I should be solving the potential as
\varphi(r,\theta) = \sum_{n=0}^\infty (A_n r^n +...
I know there is a pi phase shift when going from an area of lower index of refraction to higher. Is this phase shift still pi when going from a non-conducting dielectric with index of refraction n and reflection off a "good" conductor?
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Find the potential at the centre and at P of a hollow uncharged conducting spherical shell if a charge q is placed at a distance of 2r from centre of shell.
(r is the radius)
Homework Equations
All the charge induced on the sphere has to reside on the sphere's outer...
If there is a small object with positive charge placed above a metal plate, the object induces a negative charge on the surface of the plate facing the object. Let's call this surface as S1.
(The metal plate is initially uncharged).
But from conservation of charge, the net charge in a metal...
This seems like such a simple thing so maybe everyone can help me talk this through...
So in a simple circuit with two conductors mated by physical means (think a plug into a socket) there will be heat because there is effectively arcing between the two conductors. So everyone keeps saying it...
I need some help with my science fair project question and I want to know what metal it is honestly it has to be copper write that is what wires are made of?
Peierls distortion states that for a 1 dimensional polymer (like polyacyteline) with lattice spacing a they should have a half-filled conduction band, why?
And how does changing the lattice space to 2a cause it to form an energy gap? In my mind it should be the same as the first case...
I understand that there is no electric field inside a charged conductor, but; I don't understand why a connection to ground made on the inner surface of said sphere will flow current. Is this not correct?
1. The question:
This question is from purcell's E&M book (3.71).
(a) The plates of a capacitor have are A and separation s (assumed to be small). The plates are isolated, so the charges on them remain constant, the charge densities are +-σ. A neutral conducting slab with the same area A but...
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The following is a small concept exercise from an. EM text (Electromagnetism: Pollack and Stump). I believe I have the explanations correct, but am just looking for "peer-review" as they seem "hand-wavy":
Suppose a conductor has a cavity inside it, and there is a point...
I don't understand why there is no net electric field inside a conductor. Let's say the conductor is a sphere with excess charge. The charges will then distribute themselves towards the edges. Now, if I place a test charge anywhere except for the center of the sphere, wouldn't there be a net...
i have a doubt on this one. we know +ve charge (proton) and neutrons make the most of mass for any matter. Now consider a conductor and through induction, centre of -ve charged is moved toward the object (insulator(static charge on it) with +ve charge say). Now these two attract and conducting...
I was wondering , are there any materials , metal or others, that have ions as the charge carriers that form current instead of electrons as in most metals.?
and are the ohmic resistance in room temperature for example similar to materials were current is formed by electrons or is the resistance...
Assume a conductor in a rectangle shape for simplicity.
Now, if I only choose one side of this rectangle, and apply external electrical field ∑ only to it, what EMF would I create on the conductor? I would simply say ∑, however then I had the following idea, and I started to doubt if I create...
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Through linear conductor flows current I, with direction shown in the picture. Axis where conductor is placed is common edge of three areas with different ferromagnetic materials. They form angles θ1, θ2, θ3 (θ1 + θ2 + θ3 = 2π). If space is filled with homogeneous materials...
Hi, this is my modified post since I've been told that I have to use certain format. I hope this is good now.
Homework Statement
Copper (conductor) sphere of radious R with an spheric bubble inside placed at distance c from the center, with radius b. The metalic sphere has charge Q.Homework...