# 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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### Application of first law of thermodynamics in the case of dipole inside an uniform electric field [closed]

I was solving a question. But am not able to properly grab the concept within it. It is related to dipole within an uniform eletric field. I'm not instrested in the answer [it's not a homework ...
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### In what direction would current flow in the coil?

I have two circular coils facing each other in parallel. Through one coil current flows. I move the second coil in a parallel fashion. What is the direction of current induced on the moving coil? Acc. ...
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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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1 vote
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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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### 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 ...
1 vote
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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)=...
1 vote
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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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1 vote
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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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