# 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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### How fast does an electromagnetic field come into existence? [duplicate]

In this video by the YouTube Channel "Veritasium" it is explained, that electrical energy is in fact not travelling through the wires of a circuit (in the form of electron flow), but instead ...
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### Can Lorentz force polarize a neutral dielectric atom?

Is it possible to electrically polarize an atom (typically a dielectric) with magnetic field? For example, if dielectric fluid flows near magnetic field, does it shift each atom's positive charge down ...
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### Electric field in circuits and potential drop

With reference to the above image: Here the battery produces a constant (will it be constant? pl. explain) electric field across the length of the wire, lets say its value is $\vec E$ . This field ...
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### Electric field in the center of hemisphere shell without double/triple integrals

I'm trying to derive the electric field in the centre of a solid hemisphere of radius $R$ where the charge is distributed uniformly. I have seen different methods involving double/triple integrals ...
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### Electromagnetic fields of a spatially bounded time-dependent current which is eventually steady

So here's the set-up: I have a loop in space and fix a point $p$ outside the loop. Then I turn the current on at $t = 0$ (so the current profile is a step-function). Initially at $t=0$ the E&M ...
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### Electric field inside a wire and potential difference

Suppose I have a battery of $V$ volts and a circuit is made using it. This battery produces a constant electric field which moves the electrons thus establishing current. Now what will happen to the ...
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### Electric field inside a wire

For a uniform (constant) electric field, we have the relation $E = - \Delta V/\Delta r$. Now, if the electric field provided by a battery is constant over a constant potential difference and if we ...
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### Is electrical resistance analogous to friction?

In a circuit, an electric field is produced from a circuit element providing a voltage source. Electrons flow through the circuit undergoing collisions which provide a resistive force to the electrons ...
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### Why does the the electric field intensity is 0 inside a charged conducting spherical shell? [duplicate]

Given a conducting spherical shell with infinitesimal thickness and the radius of $R$. The shell is uniformly charged with surface density $σ$. Find the electric field intensity vector $\bf E$ at the ...
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### How can two electric plates have a potential difference if the circuit is technically incomplete?

With two electric plates, for example: When the switch is closed, wouldn't the circuit still be incomplete? So I'm not too sure as to why there is still able to be a potential difference. But if the ...
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### Creating an electric field

I'm trying really hard to finish making a Van de Graaff generator because I need an electric field to do a demonstration. I'm hoping it generates 500,000 volts. But I found some high volt generators ...
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### Conversion of potential energy of charge into kinetic energy

Suppose I have a battery of voltage v which can flow $Q$ coulomb of charge through a metalic conductor When voltage is applied across this conductor the electrons inside it get accelerated and move ...
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### Electric Field at the center of a cut portion of a sphere

Suppose we have a solid sphere of radius $R$ and of total charge $Q$ uniformly distributed in the volume. We have cut a small portion (a sphere of radius $R/2$) from inside the sphere as shown in the ...
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### Scalar potential from electric field

I am trying to calculate the scalar potential of a disk located at $z=0$. I determined the electric field along the $z$ axis \vec{E}=\frac{\sigma}{2 \epsilon_{0}}\left[1-\frac{z}{\sqrt{z^{2}+R^{2}}}\...
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### Multipoles as a superposition of dipoles?

While navigating on Stack Exchange, I was suddenly wondering about a possibility that I never saw described in my textbooks on electrodynamics. Suppose you have a distribution of electric charges in ...
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### Clausius-Mossotti factor for ellipsoides

The dielectrophoresis (DEP) force acting on a sphere involves the calculation of the real part of the complex Clausius-Mossoti factor, which is nothing but a relationship between the dielectric ...
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### Electric field from a sphere not uniformly charged

I am reading the Feynman courses. It is written inside the book that a sphere of radius $a$ charged by a surface charge $\sigma = \sigma_0cos(\theta)$ should generate an electric field with a moment ...
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### Relationship between $\vec E$,$\vec P$,$\vec D$ inside a dielectric material

If we put a dielectric material in region where an electric field $\vec E_0$ is present then, the fields that are present within the dielectric are: $\vec E$,$\vec P$,$\vec D$ . $\vec E$ is the ...
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### Force on a current-carrying loop due to a uniform electric field

Why does a closed current carrying coil experience no force when placed in a uniform electric field, whereas a charge moving with constant velocity through a uniform electric field does?
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### When an electrical field is generated inside a Faraday cage (say as in a microwave) does the cage act as a reflective surface to amplify the field?

I am familiar with the concept that electrical fields within a Faraday cage do not extend outside of the cage and that electrical fields generated outside do not extend into it. My question is -- when ...
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### Is field strength a scalar or a vector?

I'd imagine strength to be a scalar quantity. My intuition says that how strongly a force is experienced, ie its magnitude, has nothing to do with the direction it is experienced in. From what I ...
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### Confusion concerning notion and origin of electrostatic potential

An elementary circulation is mathematically defined by: $dC$=$\overrightarrow{OM}$.$\overrightarrow{X}$. Now, we aplly this to a ponctual charge: $dC$=$\overrightarrow{OM}$.$\overrightarrow{E}$ And we ...
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### Why is the electric field caused by a infinite plate the same no matter the distance from the plate?

I understand why the field is perpendicular to the plate at all distances $R$ from the plate but can't understand why the strength remains the same. If we calculate $E$ using Gauss Law I understand we ...
32 views

### How do I find the electric field at the middle point in a thin long strip whose cross section is a semicircle?

A thin long strip whose cross-section is a semicircle carries a uniform surface charge of density s on its inner surface. Find the electric field at a point O located midway on its axis. Link of ...
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### Why is voltage used when measuring the strength of a battery and not electric field?

I'm not sure how to ask this but, I started learning about electromagnetism with how charged particles behave in electric fields. This was easy and intuitive to understand. But I felt a disconnect ...
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### Why is the concept of potential used so loosely?

What does potential of a conductor actually mean? As I have understood it potential is the amount of work done by an external agent to bring a unit positive charge to a point of consideration. It is ...
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### Fourier Transform of the vector $\vec{E}(\vec{x}, t)$ and its direction

In chapter $\textit{13.3 - Density Effect in Collisional Energy Loss}$ of $\textit{Classical Eletrodynamics}$ by Jackson, it says that: The problem of finding the electric field in the medium due to ...
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### Gauss law apparent violation

If we assume to place a dipole or a quadrupole inside a Gaussian surface, then the Gauss law will give zero electric field outside Gaussian surface at any point since enclosed change is zero. However,...
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### Increasing capacitance of a capacitor [duplicate]

In my book, it's given that: ”Principle of Capacitor: In the capacitor arrangement, the increase in capacitance of a conductor is due to the decrease in potential V (charge Q remains constant) when ...
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### Dielectric material between two plates

I wonder if the capacitance is the same if we have two plates with a dielectric material between. I mean, is it the same when the dielectric material only touches one of the plates, compared with when ...
### Calculating the surface charge density as a function of $X,Y$
$x$-$y$ plane is a conducting plate stretching to infinity. A charged line is placed from $(0,0,0)$ to $(0,0,L)$. It has charge density function of ${\lambda=\lambda_L\frac{z^2}{L^2}}$. Calculate the ...