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 [tag:electricity], as questions about the phenomenon & theory of electricity do not necessarily involve the discussion ...

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87 views

Potential vs Potential Difference for a line charge

How would I calculate potential for an infinite line of charge a distance 'r' away from it? What does the reference point for potential difference mean? I know delta v = Q/(2pi*epsilon0*L)*ln(r2/r1) ...
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2answers
70 views

Parallel Connection of Capacitor

Assume Two Capacitor filled with different dielectrics with dielectric constant $K_1$ and $K_2$ respectively in Parallel connection. Then we have same voltage $V$ on both capacitors. Therefore, $$\...
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1answer
77 views

Work done by Electric Field vs work done by outside force

I'm confused as to the signage of the equation: W=qv, W=-U, W=-qv? When is work positive? When is it negative? Why is this different for the work done by the electric field vs the work done by an ...
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1answer
58 views

Why do these calculations of EM fields for a magnet and wire loop seem inconsistent?

Suppose you have a conducting circular wire loop and a magnet moving towards each other. They move along the $z$ direction with nonrelativistic constant speed $v$. Let the $B$ field of the magnet in ...
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1answer
72 views

Why a motionless proton doesn't feel any force in a magnetic field according to special relativity?

In this ( https://www.youtube.com/watch?v=1TKSfAkWWN0 ) specific video uploaded by Veritasium on YOUTUBE , we come to know about how special relativity makes magnets work. We observe that when a ...
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1answer
42 views

How soon would electrons start flowing once I closed a switch on a circuit that was one light minute away from the battery

In a circuit, how do electrons "know" when the circuit is closed? To my understanding, they do not start flowing unless the circuit is closed. How soon would they start flowing once I closed a ...
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1answer
24 views

Intersection of electric field lines where the two lines have the same slope at intersection

We know that the electric field lines cannot intersect in this way: But what about this way?(where the two lines have the same slope at the point where they touch) : Could the second situation ...
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1answer
100 views

Two capacitors in parallel vs series - electric field?

If we have two parallel plate capacitors in parallel, do the electric fields between their plates have to be the same? What happens if we have a coaxial cable of length $L$, which looks like this: ...
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0answers
14 views

Generation of negative ions in air [duplicate]

What is the main physical mechanism behind the generation of negative ions in air by a high negative voltage electrode ?
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1answer
61 views

Electric and magnetic fields with synchrotrons

Can anyone describe to me one change to the electric field and one change to the magnetic field that MUST take place as particles gains energy in a synchrotron accelerator? This could also just be an ...
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1answer
77 views

Electric field at $r=0$

How does classical physics justify the existence of an electric field at $r=0$? Is this an edge case, an ambiguity, a "does not exist"? Is this a trivial case or indicative of an actual fault in ...
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1answer
255 views

Electric Potential for Concentric Spherical Shells

If you have a charged point ($q_1=+1$) inside an initially neutral spherical shell ($q_2=0$), how would you find the following: (A) Potential at the outer surface of the spherical shell? Would it be ...
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0answers
90 views

Electric Potential for concentric spheres and charged surface

A few conceptual questions about a charged sphere inside an initially neutral spherical shell and about uniform E for a charged plane. (A) How would I go about calculating potential at a certain point ...
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1answer
70 views

Can an electric field help generate a current?

What i know or am guessing:- A moving/changing magnetic field creates an electric field. So if we take a rotating magnet near a coil of copper wire, it will induce a current right. So it means an ...
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1answer
305 views

Electric field for concentric spheres

I have a couple clarifying questions: (A) in $E=kq/r^2$ for the area between a sphere inside another spherical shell, the sphere inside is considered a point charge. However, the sphere inside has a ...
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0answers
28 views

How do you solve for flux density when you are given the E(x,y,z) and relative permittivity as a tensor?

This given material is not isotropic therefore the relative permittivity is represented as a tensor given by the matrix: $$\left(\begin{matrix} 3 & 1 & 2 \\ 2 & 3 & 3 \\ 2 & 2 &...
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1answer
28 views

Is it possible to consider loops that cut through charges when proving electric field is conservative?

My goal is to prove that the integral of E.dl along the blue curve is zero. My problem is shouldn't E field approach a discontinuity when approaching the plate? Even if we consider say a point charge ...
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1answer
45 views

Why in this problem I had to take the average of the electric field?

On an electrically charged soap bubble, acts an electric force outwards. We are given the total charge of the bubble, $Q$, and its radius, $R$. What is the value of the total force, acting to move ...
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1answer
38 views

Electric field and electric potential

I have a question about electric field inside hollow spherical conductor. I think I understand the concept of Faraday Cage that protect the cavity to get any electric field from an external source. ...
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1answer
192 views

Effect of a dielectric medium on electric field and electric flux

What is the effect of dielectric medium in comparison to vacuum on electric field and electric flux. I read that higher dielectric constant means higher relative permittivity which means more ...
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1answer
299 views

Induced emf vs Potential difference

Let a square conductor frame length l, resistance R,be pulled out with a constant velocity v from a magnetic field B perpendicular to plane of the frame .Then an emf e=Blv is produced across the frame....
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2answers
246 views

Gauss' law in differential form and electric fields

I know Gauss' divergence theorem, according to which $$\iiint_D\nabla\cdot\boldsymbol{F}\text{d}x\text{d}y\text{d}z=\iint_{\partial D}\boldsymbol{F}\cdot\boldsymbol{N}_e\text{d}\sigma$$ where $D$ is a ...
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2answers
235 views

Gauss Law - Infinite line charge

I came across a sentence which made no sense to me as I was studying the electric field of an infinite line charge: The flux through the FLAT ENDS of our cylindrical Gaussian surface is zero ...
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0answers
26 views

Effective Medium

Please consider the following problem : A plane wave of wavenumber k is incident on an infinite slab which is inhomogeneous in the z direction. Also assume harmonic time dependence and that the ...
3
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1answer
133 views

If light is affected by gravity, does that mean gravity affects electrical&magnetic fields too?

Since we observed that masses indeed bend the light, and since we consider light to be composed of electrical and magnetic fields, does that mean a single point charge will result with bent electrical ...
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1answer
28 views

Electric field uniform circle $R$ direction cancel out

I am doing a physics problem involving a uniform circle with a total charge of X, and am attempting to find the electric field on a point charge on the axis of the circle a distance of Z away. I ...
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1answer
62 views

Electric field of an ring of charge [closed]

I am told that I have a ring of charge, I am given the radius, and I am told my non uniform linear charge density ( in nC/m), I want to find the electric field given a distance I am above the center. ...
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0answers
143 views

Chapter 26 Electric Fields Physics 212

A very long sheet of charge has width $L$ and surface density $n$. The sheet lies in the $xy$ plane between $x=-\frac{L}{2}$ to $x=\frac{L}{2}$ and $y=-\infty$ to $y=\infty$. Where the radius is $r=x -...
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2answers
34 views

Finding Charge given Electric Field

This question came up in a competition, and I didn't know how to solve it. ABCD is a rectangle with width $2d$ and height $d$. At point D, there is a charge with magnitude $q_1$ At point B, there ...
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1answer
38 views

The electric field created by a uniform charge density

Given the electric field defined by: $$\vec {E(\vec r)}= x \hat {x} $$ There is no obvious contradiction with the classic electro-magnetic theory. But: $$\vec \nabla \cdot \vec E = 4 \pi \rho(\vec r) =...
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0answers
49 views

Using an Earth magnetic or electric field to fly [duplicate]

Are there possibilities to use the magnetic or the electric field of earth to let a matter flow in space?
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1answer
46 views

Flow of charges in two different materials

Consider two cylindrical conductor rods as Copper rod and aluminium rod. Their edges are in contact,that is their circular faces are in contact. Their other edges are connected to some DC voltage. And ...
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1answer
863 views

Electric Potential on an infinite plate

This is a self study question based on two videos from Khan's academy here: https://www.khanacademy.org/science/physics/electricity-magnetism/electric-field/v/proof-advanced-field-from-infinite-plate-...
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1answer
41 views

The electric field inside the shell [closed]

If we place a $+q$ charge in the center of a spherical shell, what is the electric field inside the shell?
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3answers
294 views

Difference between $E$ field configuration, sheet of charge: infinite sheet of charge, conducting vs. non-conducting

This is a very easy question, but I often confused myself. Perhaps someone could explain this concept again: A non-conducting infinite sheet of charge has the electric field configuration \begin{...
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2answers
85 views

Current due to External Electric Field

Assume a conductor in a rectangle shape for simplicity. Now, if I only choose one side of this rectangle having length L, and apply external electrical field ∑ only to it(along with the wire), what ...
0
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1answer
366 views

Flux through a sphere due to a charge outside of it [duplicate]

A point charge of $\rm+5.00 μC$ is located on the $x$-axis at $x=\rm5.00m$ , next to a spherical surface of radius $x=\rm4.00m$ centered at the origin. According to Gauss's law, the net flux through ...
3
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2answers
149 views

Flux of electric field through a closed surface with no charge inside? [duplicate]

I'm reading the Feynman lectures on electromagnetism and in Vol II, Chapter 1.4 Vol. II, Chapter 1-4 he talks about the flux of the electric field and says that flux of $E$ through and closed surface ...
4
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0answers
63 views

Electric Field due a thin arc

I have been given to calculate electric field at the centre of thin arc with linear charge density as a function of $\cos\theta$ as $\lambda(\theta)= \lambda_0 \cos\theta$ How i approached: The angle ...
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1answer
276 views

Finding the electric field at a point from half of a uniformly charged rod

The image below is a rod of length that is uniformly charged to total charge at a point along the perpendicular bisector of the rod above distance . I know the formula for finding the electric ...
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1answer
152 views

Eletric field on a semi circular ring, different charges on each quarter of a ring

In this image to calculate the net eletric field is used integration from 60 degrees to -60 degrees. Ok for me by now. But then I was doing this question, number 26: And he solves by doing that: ...
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1answer
35 views

Help with this question (Eletric Fields, Dipole) [closed]

The answer in the textbook in the solutions manual is the following: I didn't undestand the last step. He said he did a binomial expansion, I just can't figure out! Appreciate any help.
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1answer
73 views

Is it possible for a conductor initially, not to have a charge?

Well I'm confused. The thing that was implanted to me is that when I hear about conductors, some charge is present and it can move freely. Now what I want to know is that is it possible for a ...
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2answers
498 views

Why do charged objects attract pieces of paper, but not pieces of metal?

I do not understand one concept in Physics: why charged objects (eg. a charged rod or comb) attract pieces of paper when brought close to them, but do not attract pieces of metal. I know that the ...
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1answer
71 views

How to divide areas in electric field lines based on field strength?

A negative charge is surrounded by four positive charges. They are all of the same strength. The electric field lines are plotted below. I am looking for the property of the drawn 'red lines' that ...
0
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1answer
115 views

In the case of two equally charged particles, is the electric field between them incompressible? [closed]

When approach two electrons (or two protons or ...), the electric fields do not merge and stay isolated from each other. Which I borrowed from here. Is it right to conclude that in the case of ...
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5answers
313 views

Why does not a battery kept in empty space discharge on its own? If space between the terminals is empty, what prevents the electrons to flow?

Given here is the picture of a twisted battery kept in free space (vacuum). Will the battery discharge quickly? I mean, it should discharge faster than it would if we were to connect the terminals ...
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5answers
167 views

Flux of $E$ through the shaded side

A charge $q$ sits at the back corner of a cube, as shown in Figure. What is the flux of $E$ through the shaded side? One of the solution stated that. Looking at the figure, we notice two things: ...
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0answers
58 views

Electric field through closed glass tube

I have two electrodes outside a closed fused quartz glass tube. The tube is a cylinder filled with air, with two circular faces of 10mm diameter and a length of 100mm. The electrodes are pressed ...
3
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1answer
38 views

Tesla Coil stops sparking until restart [closed]

I have a tesla coil with NT-1530-OUT Transformer, 23 turns (max) primary, 1m secondary(~1600turns), with MMC and rotary sparkgap. Gets 50cm sparks but try to tune the tesla coil by shifting top load,...