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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Semiconductor conductivity increases but Fermi level decreases
I was going through this question:
Why does the Fermi-level decrease with temperature increase?
As the temperature increases though the semiconductor becomes intrinsic where number of holes equals ...
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Why can we just plus two charge directly if they don't connect each other by a wire?
Two concentric infinitely thin conducting spherical shells of radii a and b,where a<b,are charged to potentials $V_a$ and $V_b$ respectively.The inner shell has a charge and the outer shell has a ...
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If I spin a magnet in a coil which has a length parallel to the magnet’s spin axis, is a magnetic field generated along the length of the coil?
This I feel is a bit of a complicated question, so I’ll quickly try to paint as clear a picture as I possibly can:
The magnet is spinning on an axis perpendicular to its poloidal axis (the line which ...
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In what ways are the charges and surface charge densities distributed when two charged conducting spheres are connected?
When two charged conducting solid spheres(having charges Q1 & Q2) are connected,the charges get distributed in the ratio of their capacitance(C).C∝radius in case of spheres and hence charge ...
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Electrons distribution when a conductor is placed in an electric field
(This is releated to the question of how electric field inside a conductor is zero, but Im trying to focus on a specific part of that expalnation in this question, I hope you understand).
Im ...
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Charge distribution on a discharged conductor
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I am trying to prove that given a conductor with zero net charge on it then the charges necessarily distributes on its surface so that the density is zero at every point.
We can assume the ...
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If electric field inside a conductor is always zero, then why do free electrons move?
Electric field inside the conductor is zero. That means there is no electric force on electrons inside. Then how do free electrons move from atom to atom in random direction? What is the reason of ...
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Trick question: why do dielectrics and isolated conductors affect capacitance differently?
This question confused me a bit, but I figured out the answer. I just want to share this trick question here.
Trick question: Dielectric material produces net surface charge when placed in electric ...
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Are the wavefunctions of electrons in conductors localised?
In my introductory condensed matter physics class, I learnt that the solutions to the time independent Schrodinger equation in a periodic potential are Bloch states. These wave functions are ...
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Solid conducting sphere, its material, electric field and electric potential [closed]
I have tried reading multiple post from stackexchange google, but still cannot figure it out:
lets say if i wrote "A solid sphere has charge distributed uniformly throughout..."
can i ...
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Uniformly charged conductor in electrostatics
Why can we deal with uniformly charged conductors in electrostatics. The charges are on the surface. If we assume the conductor to be positively charged,then every positive charge will repel other ...
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How to use the Smith chart properly? [migrated]
In our electromagnetic waves class at our electrical engineering department, we came across the Smith chart, a valuable tool for designing transmission lines. This class covers the following topics: ...
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Are voltage and current in phase in a transmission line with a lossless medium?
In electromagnetics, E and H are in phase in a transmission line with a lossless medium.
So V and I are in phase.
But in power transmission line, usually I is lagging with V.
Since we mainly use ...
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How can flux linkage (a 3D concept) be defined for a cross section?
The authors of Power Systems Analysis calculate the inductance per unit length (henrys/meter) of a transmission line attributed only to the flux inside the conductor as "flux linkages per ampere.&...
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How electrons are shared in parallel resistance circuit? [duplicate]
In parallel resistance circuit. When electrons are shared in both the parallel resistor (different values of both resistors) .when the electrons are just to shared how did they know what resistor they ...
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Does Induction provide equal and opposite charge on neutral body? [duplicate]
Let say there is a charge '+Q' and a very long neutral rod. If the charge '+Q' is kept at distance 'd' from the long neutral rod, will the negative charge accumulated on long neutral rod(on the ...
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How to derive intrinsic impedance of parallel plate transmission line?
I've been Googling variations of this for hours but I can't seem to find any information on it and the formula my professor provided just seems to come out of nowhere and he provides no explanation or ...
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Charge distribution on conductors [duplicate]
Consider a metal sphere $S_1$ with radius $R_1$ and charge $Q_1$. If another metal sphere $S_2$, of radius $R_2$ and no charge at all, touches the first, how much charge is transferred to the second ...
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Why we need wires?
Imagine a cell(battery) bent in such a way that the two terminals face each other with some vaccuum in between...i hv confusion in basics..so pardon me...my question is why cant charge flow from one ...
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Making sense of band theory for nonmetals
For the case of metals, we observed that metals often have nearest-neighbours in excess of the maximum valency (for example, 8 for Li, which has only one valence electron) and that metals display ...
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Resistance through Tinned Copper [closed]
Too many conflicting articles from prominent electrical manufacturers; some state Tin solder on copper improves conductivity, some state it reduces conductivity at the expensive of corrosion ...
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Short circuit doubt [duplicate]
Short circuits occur when a live wire comes in contact with a neutral wire due to poor insulation and stuff, and the main gist of this word short circuit is the fact that the wire gets heated up so ...
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What is the intuition for no resistance between concentric spherical surfaces if $k = 0$ in this problem? [closed]
I've currently solved problem 5.16 in Cheng's book on Field and Wave electromagnetics. The problem is stated as:
Determine the resistance between two concentric spherical surfaces of radii $R_1$ and $...
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Is Professor Feynman wrong here?
In the Feynman Lectures on Physics, Volume II section 5-10 “The field in a cavity of a conductor” Richard Feynman states the following in the penultimate paragraph:
“… no static distribution of ...
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What happens inside a conductor when the current faces resistance?
According to my book resistance depends on the the number of collisions free electrons suffer in any conducting device. Now insulators have no free electrons so how do they have high resistance like ...
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Properties of coefficients of potential in multiconductor systems
In multiconductor systems, it is stated that the coefficients of potential have symmetry.
\begin{matrix}\phi _{1}=p_{11}Q_{1}+\cdots +p_{1n}Q_{n}\\\phi _{2}=p_{21}Q_{1}+\cdots +p_{2n}Q_{n}\\\vdots \\\...
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Microscopic explanation of potential drop in resistors
I'm trying to understand from basic principles why a resistor causes a drop in potential. Going beyond Ohm's law (which doesn't really explain it microscopically), it seems that each side of the ...
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Charge distribution in a current carrying wire
There is a channel on youtube called Electroboom, who has a video titled How Right IS Veritasium?! Don't Electrons Push Each Other?? related to the surface charge distribution in a current carrying ...
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Why is the current the same after passing through a resistor even when the drift velocity goes down?
A resistor converts some of the electrical energy into heat energy, implying that the energy goes down, implying that the force with which an electron moves, and consequently, the drift velocity goes ...
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Electric field inside open conductor
Is the electric field zero inside a metal conductor whose surface doesn't enclose a volume ideally, that is, a conductor that is almost a closed surface, except for a small hole?
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Why do two infinite planes contribute to Electric Field but not two surfaces in co-axial cylinder
I understand why the electric field between two infinite planes is $\frac{\sigma}{\epsilon_0}{\vec{e_z}}$. Both planes contribute to the field - the upper positive charged plane "pushes" ...
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Electric Field in- and outside a conductor - calculation and concept [closed]
So I'm currently self-studying ED by Griffith, as I just finished the first chapter I decided to come back and do the problems.
...
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Rigorous definition of the perfect conductor in macroscopic electrodynamics
Zangwill (in Modern Electrodynamics -- most of this discussion relates to Chapters 5.1 and 5.2 if you have access to the book) defines a perfect conductor as a macropscopic model for certain matter in ...
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Condensation on Mirror
When taking a hot shower I notice that moisture forms on the surface of my mirror. Mirrors are insulators so why does water vapour condense on the mirror? I've seen explanations that state that when ...
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Possibility of continued partial electric discharge
Consider a pipe with a tear drop shaped conductor located at the center and an electric field parallel to the pipe in it. The electric field is stronger at the tear-drop conductor and looks as in the ...
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Physical meaning of functional derivative of Coulomb potential energy
I am considering the problem of a conductor of arbitrary shape, and I want to prove (I reckon it's possible) that the field inside the conductor is zero assuming only that the charges are in a ...
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Does a conductor block the electric field across them?
So I was learning electrostatics and came across this statement that the net electric field inside the bulk of a conductor (at equilibrium) is zero. This happens because the free charges inside the ...
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Difference between uniform and non-uniform conductor [closed]
Am I correct to say that a uniform conductor is cylindrical, while a non-uniform conductor can have any geometry as long as it is open at both ends.
The textbook does not seem to define these 'uniform'...
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How different material capacitors can develop different charges?
I learned in a video tutorial that same battery could produce different charges based upon different capacitance of the materials used.
Also A capacitor fully charged has the same voltage as the ...
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Electric field produced by charge inside thick spherical shell
It is a well known result that the electric field produced by a charge $q$ inside a thick conducting spherical shell outside is the same as the field produced by the same charge placed at the centre ...
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Wouldn't every material act as an insulator on 0°K?
I was going through an example of conductors and insulators in terms of energy gap and that got me thinking. For conduction, free electrons need to be able jump from the Valence band to conduction ...
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Static electrification of the same material at different temperatures
In the following books it is stated that when you have 2 samples of the same material at different temperatures and they are rubbed together, the colder one gets electrified positively, the hotter one ...
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Conductor-Dielectric Boundary Conditions
We have a conductor of resistivity $\rho$ and has a boundary with a dielectric of permittivity $\epsilon$ and we have displacement vector $\vec D$ at an angle $\alpha$ with normal to the boundary and ...
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Why does a current carrying wire not attract small magnetic metal pieces?
If the current flowing in the wire produces a magnetic field, why are are small pieces of ferromagnetic metals not attracted to the electric wire?
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Conducting Shell and a Metal Sphere
I am have a doubt regarding the topic Conductor in Griffith's text book of Electrodynamics.
Griffiths states that, a perfect conductor contains infinite amount of charges, and a metal resembles that ...
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Why $V$-$I$ curve for good conductors is not a perfect straight line?
I was reading a text from my school textbook it read
"the $V$-$I$ graph for good conductors is not a straight line"
but they didn't explain why. So why a conductor not completely following ...
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Why more charges normally accumulate at the position with a larger curvature on a curved surface?
For a curved interface between two adjacent poorly conducting materials with different electrical properties, when applying a DC voltage difference between the two materials, as in a capacitor, the ...
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Hollow conductor for transmission line
A hollow conductor can transfer almost the same current when compared to a solid conductor with less material requirement due to the skin effect. But still, we use solid stranded conductors for a ...
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Charge in surface of hollow conductor when has a dielectric inside
I have seen multiple times answered the question of what charge will appear at the sides of a hollow conductor when you place a charge in the center of the hollow sphere: if you place Q inside the ...
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Can the Hagens-Ruben equation be applied at radio frequencies?
Wondering if you can apply this equation to RF (ex. microwave bands). I notice when comparing copper and aluminum they both result in ~0.999.
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