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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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
67 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
284 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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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 ...
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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 ...
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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
161 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
264 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 ...
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2answers
238 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
234 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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25 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 ...
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1answer
131 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
132 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
32 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
37 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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46 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
787 views

Electric Potential on an infinite plate

This is a self study question based on two videos from Khan's academy here: ...
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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
282 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 ...
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2answers
74 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 ...
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1answer
339 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 ...
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2answers
145 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 ...
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0answers
52 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
273 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
139 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
72 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
468 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
68 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 ...
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1answer
102 views

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

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
298 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
148 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 ...
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0answers
55 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 ...
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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 ...
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1answer
97 views

Why do charges move at the rim of the “charged-disk” conductor in response of the field created by themselves?

Okay, one statement from Purcell's book goes like: [...]Thus, we find the potential at $P_2$: $$\phi = \frac{1}{4\pi\epsilon_0} \int_{-\pi/2}^{\pi/2} 2\sigma\cos\theta d\theta = \frac{\sigma ...
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0answers
12 views

Net electric field of a nanowire in the vicinity of a quantumdot

I know how to find the electric field when both nanostructures are same and in the vicinity of each other. However, when it comes to nanostructures of different dimentionality (ie.nanowire and a ...
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1answer
64 views

Electric field at location of a charge due to the charge itself?

Suppose a charge $Q$ is put in the space at point $(x',y',z')$. What is the electric field value at point $(x',y',z')$?
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3answers
230 views

Drawing the lines of force for an electric field varying in magnitude but having a constant direction

How will the electric lines of force look for an electric field varying in magnitude but having a constant direction, say along +ve z axis ? According to me, since the electric field is varying in ...
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1answer
174 views

What is the meaning of $\vec{E}\times\vec{B}$?

Consider that for a single $\mathbb{R}^3$ point-source emitter of RF, the $\mathbf{E}$ and $\mathbf{B}$ fields (when treated as transverse sinusoids and ignoring interference properties) are always ...
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2answers
135 views

Why does the electric polarisation (polarisation density) have this direction?

It can be inferred that the amount polarisation $ P $ is dependent upon and proportional to the magnitude of the electric field $ E $ applied: \begin{equation} P \propto E. \end{equation} This ...
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2answers
182 views

Electric field in a non-uniformly charged sheet [closed]

So if we have a large sheet that is not uniformly charged and is NOT a conductor, how can I find an expression for the electric field everywhere? Things we know about the sheet: the width is 2b it ...
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2answers
107 views

When is work done on or by something?

An example, here what my textbook says: When charges are released In electric fields charges experience the force causing them to accelerate along electric field vectors. Positive charges ...
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1answer
97 views

Electric field between capacitors [closed]

A parallel-plate capacitor consists of two parallel, conducting plates of area $A$, separated by a distance $d$. Each carries a charge of magnitude $Q$; positive on one, negative on the other. ...
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0answers
19 views

Why the magnitude, $E$, of the field vector is different for every sets of (parallel) plates?

This is quoted my textbook. I wonder why we can't reproduce the same magnitude on a different set of plates, if we make them the same size, same charge, and having the same electric potential, and ...
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1answer
184 views

What do field lines between two like-charged parallel plates look like?

I couldn't find any image to answer my question on Google. But I guess it looks somewhat like this, correct?
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3answers
144 views

Which one of the two objects does the gravitation force vector point to?

My book tells me that the arrowhead should point to whichever is responsible for the field. Am correct in a assuming that it's whichever has the larger mass or bigger electric charge?