Questions tagged [electric-fields]
For questions that utilize the concept of electric fields (commonly denoted by the letter E), or for questions whose answers likely involve electric fields. More specific than the [electricity] tag, as questions about the phenomenon & theory of electricity do not necessarily involve the discussion of fields.
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Calculation of current density distribution in ferromagnetic strip with barber-pole geometry
I'm working on a mathematical model of an AMR sensor, the basis of which is a current-carrying thin ferromagnetic film with highly conductive strips placed at a 45° angle on top of the film:
The ...
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Magnetic field insideof a capacitor in the moment of discharge [closed]
Flat capacitor is filled with weakly conducting dielectric of permittivity $\varepsilon$. Capacitor plates are round shape of radius $R$. Find magnetic field inside the capacitor in the moment of ...
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Mathematical error in calculating $E$ field in this set up [closed]
Suppose we have a infinite plane with thickness $h$ parallel to the $xy$ plane and spans from $z=0$ to $z=h$. Let the charge on it be $q=kz$ with $k$ as a constant. Using Gausses law, one easily finds ...
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Computing the potential difference between two points using $\ \vec{E} \>=(xî + yĵ + zk̂)\frac{kQ}{(x^2 + y^2 + z^2)^{3/2}}$ [closed]
The potential difference between two points, A to B, is given to me as
$$ΔV= -\int\limits_A^B \vec{E} \cdot d\vec{r}\ . $$
Since this is my first time seeing something like this as a first-year ...
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Can Sagnac effect be observed in coiled, rotating electrical cables conducting electric signals?
Can Sagnac effect be observed in coiled, rotating electrical cables conducting electric signals, in a similar way to that observed in coiled, rotating optical fibers? And if so then who demonstrated ...
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Is Faraday's cage described in electrostatic 100% insulated?
I apologies if my wording is bad or it is duplicate.
I'm new to Electrostatics. During the topic of conductors & electric
field I was introduced to Electrostatic Equilibrium state in which
the ...
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In an electrostatic field with zero divergence everywhere, where is the charge located?
Purcell in section 2.17 discusses the electric field $E = <Ky, Kx, 0>$, which has field lines in the shape of a hyperbola, $\phi = -Kxy$, zero curl, and zero divergence. Purcell states that ...
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Variance of Capacitance
I'm studying Capacitance as a high school student and I have come across few things which I am puzzled about.
I understand that bringing a negatively charged conductor near a positively charged one ...
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Charge $Q$ is uniformly distributed over a ring of radius $R$ [closed]
If now a small portion of length $d$ is removed from ring, then electric field at centre of ring becomes _____________.
How to approach this question? I don't know what to do.
They just cut and remove ...
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Why can't we calculate potential at a particular point due to an infinitely long thin wire with uniform positive linear charge density?
I read in theory that we cannot calculate at a particular point due to an infinitely long thin wire with uniform positive linear charge density. Instead we can only calculate the potential difference ...
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What is the meaning of $\vec H$ with respect to the total field?
Now before saying anything, I have seen the similar questions in this page regarding $\vec H$ but no one has fully convinced me yet, since I will try to give another perspective to this question.
We ...
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Energy of electric dipole near a conducting plate [closed]
How to find the energy of the dipole when put near a conducting plate at distance $a$ with angle $\theta$ from the normal vector to the plate? I used the method of images and the formula $U=-\vec{E'}\...
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Why is the expression for the electric field vector on a point in space originating from a moving point charge this way? [duplicate]
I was studying light as electromagnetic radiation in Feynmann's lectures book (Vol. 1, Ch. 28) and, in explaning how radiation works, he gives the following expression for the electric field at a ...
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Is the electric force really proportional to the charge it acts on? [closed]
Of course we all know Coulomb's law, which includes the fact that the electric force experienced by an object is proportional to its charge. My question is: Does this hold to the best of our current ...
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How current is induced when there is a change in external magnetic field?
If still charges in a wire loop do not respond to a(or have their own) magnetic field, then how is current is generated by changing a magnetic field? And why only a changing magnetic field? What ...
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How do charge carriers "know" how much voltage to use for work in a specific component? [duplicate]
I understand the basic concepts of voltage pretty well, I think. However, one thing has been bugging me which I can’t seem to figure out.
How does a specific charge carrier "know" how much ...
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Why don’t charge carriers constantly accelerate in an electric circuit?
With my current knowledge of electric circuits and electrostatic fields, I would expect that the electric field generated by the potential difference of, say, a cell should exert a constant force upon ...
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Explaining Faraday's Law With Lorentz Transformations of $E$ and $B$ Fields
I've searched around for this but haven't come across a totally satisfying explanation yet. I'm trying to build a relatively simple model of how the Lorentz Transformations of the $E$ and $B$ fields ...
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EAD Thrust with electric field [closed]
I am interesting in making a ionic thruster and I want to know how to calculate the thrust generated by it. i am think that having the voltage,current, of electric field using gauss's law could help ...
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Why is there no negative sign in the linear form calculation of voltage but there is a negative in the integral form? [closed]
The formula for voltage given $\vec{E}$ and $d$ is $$V = |\vec{E}| d.\tag{1}$$
However, the formula is also $$V = - \int \vec{E} \cdot dr. \tag{2}$$
Why does one of these formulas have a negative and ...
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How do the forces involved in EMR continue to occilate past emmision of a photon
If electric fields are created by an accelerated charged particle, such as an electron, and magnetic fields are generated by electric fields in motion, what are the individual fields that make up ...
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Is the superconducting wire in a equilibrium DC circuit free of surface charge?
Suppose we have a closed circuit composed of a time constant voltage battery, a resistor and superconducting wires connecting them in series. In the equilibrium state, both the free charge the ...
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Reverse electrowetting on dieletric using air bubble displacement for electricity generation
I read this research paper and it uses bubbles to change the electrolyte and electrode interface, thus causing a change in capacitance as the bubble forms and exits the electrolyte.
For reference: ...
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How does an Electromagnetic Accelerator work?
I've recently watched this video about an electromagnetic ring accelerator. I get how it works:
it uses controlled electro-magnetic coils to accelerate metal balls'
Passing trough one of the coils ...
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Can dielectric coated metal wire mesh in electrolyte be a capacitor
Since capacitance is proportional to the area of the plates, why don't we just make a mesh out of metal wire (plate #1) and coat it with a thin layer of dielectric material, then submerge this mesh ...
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Is there a reason why when a parallel-plate setup is immersed under water, the potential difference between them reduces?
I will elaborate upon this question as follows.
I was trying to devise an experiment to observe equipotential surfaces of different charge configurations, using a movable probe connected to a ...
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How to know which formula to use for the electric field of a conducting plate of charge? $𝐸=σ/2ε_0$ or $𝐸=σ/ε_0$? [duplicate]
I'm so confused right now as I have come across questions regarding the E.F of a conducting plate of charge.However some questions use 𝐸=σ/2ε0 whereas others use 𝐸=σ/ε0 and I genuinely don't know ...
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Why electric potential can be evaluated by conservative electric field?
The definition of electric field is following:
The electric field is defined at each point in space as the force per unit charge that would be experienced by a vanishingly small positive test charge ...
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Which theory/model explains electrons movement inside a transmitting antenna? [closed]
I have an understanding of electrical circuits, however I am very interested to know more about electromagnetic waves radiation.
In particular I want to know how an oscillating voltage causes the ...
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Exact Definition of electrostatic field
Some documents define an electrostatic field as the electric field of a stationary charge or steady current.
However, in other documents, they are defined them as electric fields satisfying $\nabla \...
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Why electric field is unaffected due to dielectric shell?
I am reading Grifith Textbook and came across this example(Ex 4.5 in 4th edition).
A charged sphere of radius 'a' is surrounded by a dielectric shell with outer radius 'b' and inner radius 'a'.
Using ...
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What is $E$ with respect to the relation between an electric field and its polarization density?
To avoid confusion let:-
$E_0$ be electric field we applied, $E_p$ be electric field caused by polarization and $E_n$ be net electric field i.e. $E_n = E_0 - E_p$
In the relation
$P=\epsilon_o\chi_eE$ ...
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Definition of electrostatic field [closed]
In wikipedia about electric field, it define electrostaatic field as electric fields that do not change with time.
And article about electric potential, it define electrostatic field is a vector ...
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Why is AC current attractive and DC repulsive?
I want to know whether alternating current will hold you to stick to the socket or throw you away and why?
In my textbook it is written that alternating current is attractive in nature but when i ...
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Increase of potential when charging a capacitor
I have seen previous posts on why the potential of a fully charged capacitor is equal to that of the external battery. But I was not satisfied by the analogies made that charges will repel each other ...
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What is the intuitive reason why Ampere's law is incorrect?
I don't understand why Ampere's Law for magnetic fields is wrong. So initially, we got taught it as the following:
$$\vec\nabla\times\vec{B}=\mu_0\vec{J}$$
and this turns out to be wrong. I also ...
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The total energy of an atomic supercell with a local dipole moment in an external electric field
How to define the total energy of an atomic supercell with a local dipole moment in an external electric field?
The figure below illustrates the two cases of the local dipole moment within an atomic ...
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Unconvincing sentence in wikipedia
I'm studying about electric field and referring to an article about electric field in wikipedia
And in here, there are some doubtful sentences:
The electric field is defined as a vector field that ...
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Electric field inside wire [duplicate]
So I m a high school student and I learned that electric field inside conductor is 0 when it is placed in external electric field due to induced Electric field inside.
How can electrons flow if E(net)=...
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Potentials of two near conductors
When two conductors (let's say spherical) of charges $q_1$ and $q_2$ and radii $r_1,r_2$ respectively are brought and connected by a metal rod,we know that flow of charge occurs unless potentials are ...
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A question about Coulomb's law for one moving and one stationary charge
let one charge is moving and another charge is stationary (compulsory). Then the electric force between them can be calculated by coulomb's law?
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In a conductor responding to an external $E$-field do the electron clouds just shift slightly or do the electrons fully dissociate to go to one side?
For a conductor in an external field, I would like to know whether the electron clouds of each atom, just shift slightly (resulting in positive charges just on one edge, and negative charges just on ...
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Electron Orbit at the Null Point (DC sputter coating)
This situation pertains to 'thin film sputter coating.'
Suppose I have some magnets in between a high voltage anode and cathode in a suitable vacuum. I understand that the electrons get trapped in the ...
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When electrons go to the outside surface of a conductor why doesn't that create an electric field pointing radially outwards? $E$ is supposed to be 0
If an isolated conductor has a net zero charge and is not in an external field, would the free charges still move to the surface of the conductor eg. a conducting sphere? Wouldn't this create an ...
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Why are the total and free EM fields mixed together?
For calculating the work done on a medium by an electric field: $đW = \vec{E} \cdot d\vec{P}$ but for magnetic fields: $đW = \mu_0 \vec{H} \cdot d\vec{M}$. For impedance, $Z = \frac{E}{H}$. Why is the ...
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Purpose of Using Taylor Series and Multipole Expansion to Approximate Potential
I'm currently taking a third-year electromagnetism course (we use Griffiths), and we have begun covering approximations of our potential function, $\text{V} =\int\frac{k \text{dQ}}{\textbf{||r||}}$, ...
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Can two different electric field exist for the same potential?
Take the electric field due to a electric dipole. If i do the line integral of this field from infinity to a point 'r' radially then \theta component of field has no role in this integral. So can two ...
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Missing Scaling Factor of the Electric Field of Hermite-Gaussian Modes
I am currently looking at A. Yariv's book "Introduction to Optical Electronics" 2nd edition. In Chapter 3 "Propagation of Optical Beams in Homogenous and Guiding Media", Yariv ...
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Same behaviour of EM radiation at the polarisation grid and at the double slit?
In a diffraction grating, the EM radiation is polarised after passing through the grating, i.e. the electric and magnetic field components are aligned by the grating bars, one component parallel, the ...
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What is the solution of wave equation for a moving charge?
The electric field of a point charge at rest in an inertial frame is static in the frame. Any location outside the charge follows the Maxwell equations in the vacuum, and as a consequence the wave ...
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