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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Formula for discontinuity of electric field across boundary

The formula for the discontinuity of the electric field across a boundary is given by$$\vec{E}_{\text{above}} - \vec{E}_{\text{below}} = \frac{\sigma}{\epsilon_0} \hat{n}.$$ In the derivation of this ...
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0answers
24 views

Electric Field around Uniformly Charged Rod [on hold]

Question: A uniformly charged rod (length = $2.0~m$, charge per unit length = $3.0~nC/m$) lies on the x-axis. In consultation with your lecture notes, calculate the magnitude of the electric field at ...
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1answer
38 views

Effect of test charge on electric field intensity

Obviously on the macroscopic scale, having a test charge being a proton produces no noticeable change in the electric field produced by a charged body. However, on the microscopic level this would ...
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2answers
26 views

Charge distribution on a conductor surface

I understand that if a conductor was charged with a charge of say 1 coulomb, the charge would spread uniformly over it's entire surface to neutralize any difference in potential. However, and though ...
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1answer
54 views

Removing an electron from a conductor

I'm trying to understand how to think of and visualize a conductor where charge is added. As I understand, conductor are defined as materials (where the nucleus is stationary) that permit electrons ...
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2answers
56 views

Significance of electrical fields of infinite objects

I've noticed a pattern with the electric fields of charged objects of infinite dimensions. A point charge, which can be considered a charge of 0 dimensions, has an electric field that goes as $r^{-2}$...
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0answers
19 views

Field due to bound charges in matter [closed]

What is the field due to a long cylinder that carries uniform polarization perpendicular to the axis? I am not able to get the answer using the expressions for the surface bound charge density and ...
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0answers
31 views

Discontinuity of electric field formula [closed]

I'm trying to understand where the formula for the discontinuity of an electric field when you cross a uniformly charged surface comes from: $$\vec{E}_{\textrm{above}} - \vec{E}_{\textrm{below}} = \...
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0answers
19 views

Electric field inside hollow metallic sphere which is not closed

Suppose I have a charged hollow metallic sphere. It is sure that the electric field inside the sphere is zero, in static case. ( I got explanation for this from the previous discussions in this site). ...
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1answer
49 views

Induced motional EMF where the wire is stationary and the field source is moving?

If a wire is moving in a magnetic field $B$, there is a Lorentz force acting on both the postive and negative charges, separating them to create an electric field, which is a great explanation to aid ...
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3answers
64 views

Intuitive explanation for uniform electric field between capacitor plates

Could anyone explain why the intensity of the electric field between plates of a charged capacitor is constant? Moreover, the varying the distance between plates doesn't change the electric field ...
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2answers
58 views

What's the difference between $E=\frac{F}{q}$ and $E=\frac{kQ}{r^2} $? [closed]

Can $E=\frac{kQ}{r^2}$ only be applied to situations outside of parallel plates?
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2answers
53 views

Theoretical questions regarding the electric field

I found some theoretical questions in an old test of my school, and would like some help with the ones I cant answer: It is said that the electric field is an intermediary of the electric ...
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1answer
53 views

How to set up line integral of electric field? Confused over notation

In multivariable calculus the line integrals was parameterized and denoted: $$ \int_C \mathbf{F} \bullet \, d\mathbf{r}=\int_D\mathbf{F}(\mathbf{r}(t)) \bullet \frac{d \mathbf{r}(t)}{dt} \, dt $$ ...
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1answer
100 views

Find magnetic field of parabaloid-spiral particle path

Given the components of the particle's path (tcos(at), tsin(at), R(x^2 + y^2)), where a and R are constants, how can I find the magnetic force causing this? I would like to understand if this can be ...
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0answers
41 views

Refraction of the electric field lines, at the interface of separation between two conductive media

Suppose we have 2 media with electrical parameters ${\varepsilon _1},\,{\sigma _1}$, respectively ${\varepsilon _2},\,{\sigma _2}$, separated by the plane surface $\Sigma $; electrical charge surface ...
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1answer
41 views

How to understand the electric-field operator in quantum optics?

I know the positive field operator $\mathbf{E}^{+}$ is actually an annihilation operator $a$ while the negative field $\mathbf{E}^{-}$ is a creation operator $a^{+}$. I also learned that the ...
5
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3answers
184 views

How to show mathematically that the electric field inside a conductor is zero?

The electric field is characterized by the equations $$\nabla\cdot \mathbf{E} = \dfrac{\rho}{\epsilon_0}$$ $$\nabla \times \mathbf{E} = 0$$ Or equivalently, $\nabla^2 V = -\rho/\epsilon_0$ and then ...
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1answer
31 views

What is the method to find field at the center of a conducting shell due to induced charges due to an outside charge? [closed]

For example, if we had to find the field at Q1 due to the induced charges on the outside spherical surface ,what should be our approach? According to me, as the induced charges due to q2 on the ...
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2answers
34 views

Instantaneous transfer of information?

If suppose there is some charge which is not under influence of any other thing. Let us for observation surround this charge with circles of pointers pointing in the direction of its field. If I move ...
6
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1answer
135 views

What force causes the induced EMF of a loop? And, the difference between a loop EMF to motional EMF?

If a loop of wire is placed perpendicular to a changing magnetic field, there is an induced EMF such that the induced current is flowing in a direction to create an opposing magnetic field like this ...
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1answer
25 views

Measurement of electrostatic induction

How is it with the electrostatic induction measurement? Everywhere you can read about the effect of electrostatic induction but I still can't found any detailed explanations or quantitative ...
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1answer
28 views

Why does the metal ball have no appreciable charge?

here is the question: A hollow conductor is positively charged. A small uncharged metal ball is lowered by a silk thread through a small opening in the top of the conductor and allowed to touch its ...
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0answers
36 views

How inversion layer shields electric field?

This question is somewhat relating to electronics but I think it fits better with physics. The leccture here (slide 13) shows that the gate to body capacitance (Cgb) in linear region is 0. However, ...
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1answer
26 views

Electric field of a line charge, along itself

look at the pic : What is the electric field in along the line of charge with charge density $\lambda$ and length $L$. Is the electric field zero along the line without any difference in height?
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1answer
39 views

Quadrupole moment of point charges?

We know that due to expansion, the Quadrupole potential equals $$1/4\pi \epsilon r^3 . \int (r^\prime)^2(\frac32. \cos^2\theta^\prime-\frac12)\rho(r^\prime)d\tau$$ but what is the equation for point ...
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0answers
44 views

Why does the polarization vector P depend on the net electric field and not the original one?

P= χε0E, where E is the net electric field from the effects of both free and bound charges. But E=(σfree-P)/ε0 So E itself depends on P. My concern is, isn't this circular? ...
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0answers
15 views

Can DC electric field be regarded as a quantum harmonic oscillator? [duplicate]

The essence of quantum theory of the radiation field is the association of a quantum harmonic oscillator with each mode of the field. However, in the case of DC electric field, can we describe DC ...
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0answers
31 views

Regarding the zero internal electric field in a conductor (electrostatic case)

Let's say we have a homogenous electric field in the $z$-direction. For computational simplicity let's say we have a thin sheet of metal covering entire the $x$-$y$ plane. The answer here is straight ...
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1answer
30 views

Electric Field of Bar [closed]

Problem: Positive charge $+Q$ is distributed uniformly along the positive $x$ axis from $x = 0$ to $x = a$. Negative charge $-Q$ is distributed along the $-x$ axis from $x = 0$ to $x = -a$. A point ...
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2answers
54 views

Electric Field of a Disk an Infinite Distance Away

The electric field of radius $R$ and a uniform positive surface charge density $\sigma$ at a distance $x$ from its center is given as $$E = \frac{\sigma}{2 \epsilon_0}\left( 1 - \frac{1}{\left(\frac{...
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1answer
31 views

Electric field created by a battery

If I create an electric field using a battery between two parallel plates and leave the battery connected, will the electric field always exist for as long as the battery lasts, including normal self ...
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1answer
45 views

Walter Lewin demo and question about how Electric fields change

This question is related to Walter Lewin "Complete Breakdown of Intuition" question asked earlier. Imagine an area where the magnetics flux is changing and the electric field lines form circular loops ...
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1answer
43 views

What are dimensions of co-ordinates which are used to define an electric field?

A possible electrostatic field is: $ E_x = 6xy$ $ E_y = 3x^2-3y^2$ $ E_z = 0$ Suppose we are using SI system. So unit for components of field is volts/meter. Then what are dimensions of $x$ and $...
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1answer
33 views

Electric Field under Time reversal

We know under time reversal electric field does not change direction. I am doubtful about it. Imagine an electric field parallel to x-axis (in positive x direction) and a charge moving parallel to ...
5
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1answer
74 views

What happens to the electric field lines when an electron and positron collide? [duplicate]

A month back I began my course in classical electrodynamics. I know about the field lines of moving charges. But I have this question that if an electron and a positron are situated some distance ...
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1answer
29 views

Electrical gradient

I'm a zoology minor and I'm trying to understand electrical gradient. I found this explanation in an authentic website but cannot undertand it fully. An unequal distribution of charges across the ...
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2answers
43 views

Electric Field and Force from four particles

Four charged particles are arranged in a square as shown below, with A=3, B=4, and C=5 (a) Determine the electric field at the location of charge q. (Use the following as necessary: $q$, $a$, and $...
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0answers
30 views

Can accelerated charged particle gain energy from charged medium? [closed]

Suppose a charged particle is moving in a medium. If it is accelerated, it is well known that it radiates energy (even in the vacuum). I was wondering if the charged particle would accelerate through ...
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2answers
91 views

Problem understanding energy of a electric field

I just finished classical mechanics, and waves and have started electromagnetism. I have studied upto electric fields, potentials and conductors in a static field and have just entered capacitors. And ...
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1answer
56 views

Divergence of $\frac{e^{-br}\hat{r}}{r^2}$ in electrostatics [closed]

My question is how to calculate the divergence of a vector field (Electric field) given as: $\vec{E}(r)=\frac{e^{-br}\hat{r}}{r^2}$. Or more generally how to approach finding the divergence of a ...
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2answers
66 views

Why does there have to be an electric field if there is potential difference?

I read in a few books that there is always an electric field if there is an electric potential. I went through this but the question on this page only states that there is an electric field and it is ...
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2answers
56 views

Electric field $E$ due to a dipole moment

Why is the formula of $$E = kp/z^3~ ?$$ Why is it $z^3$ ? I want a physics answer not math please.
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2answers
36 views

How to find electric potential from electric field? [closed]

How to find potential difference when electric field is given ?
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1answer
35 views

What is the gravitational/electric/inverse-square field inside a cylinder?

I've read from the shell theorem that an inverse-square potential has zero field inside a spherical shell. What about the field inside a cylinder? Are objects inside a long cylinder attracted to the ...
0
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1answer
37 views

Force between the plates of a capacitor

As we know that the electric field between two parallel plates of a capacitor is $$E=\frac{\sigma}{\epsilon_0}$$, so the magnitude of force exerted by one plate on the other should have been $$F=QE$$. ...
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1answer
19 views

The direction of electric field in a thin hollow cylindrical insulating shell

Consider a thin hollow cylindrical insulating shell like the one above draw in 3D-coordinate with Z-axis going out of page and is centered at the origin of XYZ axis. It has electric charge +Q ...
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2answers
40 views

Determination of the electric field of charged object using Gauss's law

when we determine the electric field of a charged rod of infinite length,we consider a circular cylinder to be the gaussian surface for convenience.In the case of a charged sheet we choose the ...
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1answer
77 views

Does changing a closed surface in the manner outlined contradict Gauss' Law?

As I understand it, Gauss' Law states that the electric flux on any arbitrary closed surface is equivalent to the sum of all charges enclosed within the surface times a constant. Mathematically, this ...
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0answers
41 views

Determine potential function given initial conditions?

Assuming a radially symmetric circular disk (let's say r=1). Given two simple initial conditions: Potential at the centre is 4 V Potential at the edges is 0 V How would I determine the potential ...