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 ...

learn more… | top users | synonyms (1)

0
votes
0answers
19 views

insufficient electrons in a conductor [duplicate]

We all know that if an electric field is applied across an isolated conductor, then charges are induced at either surface such that the net electric field inside becomes zero. Now if the applied ...
-1
votes
1answer
87 views

Finding the direction of the electric field of several charges? [closed]

A clock has negative charges -q, -2q, -3q,...., -12q fixed at a the position of the corresponding numerals on the dial. The clock hands do not disturb the electric net electric field due to pont ...
1
vote
0answers
42 views

What would happen if…? (Scenarios involving a ball in an electric field) [closed]

First I shall define two table tennis balls: Ball $A$ is coated with a conducting material and ball $B$ is an insulator. Then I'll define two scenarios: Scenario $I$ is a ball held from a ...
-2
votes
1answer
64 views

Finding V in a electric field? [closed]

How will we find $V_{ab}$ when $\vec E = (2i+3j+4k)$ N/C , $\vec R_a = (i-2j+k)$ m and $\vec R_b = (2i+j-2k)$ m ? I know $\vec E= -\frac{d V}{d\vec r}$, but I don't know what should be my initial ...
1
vote
1answer
207 views

Why does electric field remain constant in parallel plates when distance changes?

Given the formula E0 = ∆V/d, why does electric field stay constant when distance changes? If a property of parallel plates is that ∆V is constant, shouldn't E0 change as d changes?
0
votes
0answers
10 views

Electric field between electrodes of different shapes [duplicate]

How to calculate electric field between two electrodes - square and circular?
1
vote
1answer
67 views

How is the charge concentrated at the centre of shell for calculating potential from it? [duplicate]

While calculating electric potential due to a spherical shell at a point outside the shell, why do we say that the entire charge is present at the centre of shell? Is this true even if the charge on ...
4
votes
1answer
812 views

Do high voltage power lines attract lightning strikes?

I always thought that high voltage power lines would attract a lightning strike more than other structures in the same area. Turns out I was wrong. My neighbor's chimney got struck by lightning and it ...
0
votes
3answers
347 views

Does a conductor need to touch the battery terminal for electric field to be set up inside it?

I understand that an electric field is setup inside a conductor when it is connected to the terminals of a battery and that this field is caused by induced surface charges on the conductor. These ...
0
votes
1answer
172 views

Is there a surface charge density?

Consider a dielectric sphere placed within a dielctric medium. There is a uniform electric field $E_0$ present throughout in the medium. Would there be surface charge on the sphere?
0
votes
3answers
145 views

Why the electric field inside a conductor is zero? [duplicate]

In electromagnetism books, such as Griffiths or the like, when they talk about the properties of conductors in case of electrostatics they say that the electric field inside a conductor is zero.
0
votes
1answer
490 views

Electric Field at surface/side of cylinder [closed]

I know I can use Gauss's law to find the Electric Field inside and outside the cylinder very easily. We can select Gaussian surfaces for different cases (i.e. $r \lt R$ and $r \gt R$, where $R$ is the ...
0
votes
1answer
129 views

The force on an infinite line of charge perpendicular to a on a rod of charge

Essentially the question is to calculate the force exerted by a charged rod perpendicular to an infinite line of charge: $\vec{F}_{\text{rod}\rightarrow \text{line}} =\dots$ My question is it okay to ...
4
votes
1answer
191 views

Simulate / plot electrostatic field

I have something like this: For given voltage (9 V red wire, 0 V blue wire) I want to simulate electrostatic field. I already know, for example that in the point (10.5;0) there are 10 V and etc. I ...
1
vote
1answer
226 views

Find the points where potential is null

Let's say we have two charges called $q_1$ and $q_2$, respectively $20 \, C$ and $-40\,C$, at a distance $d=1\,m$ We want to find all the points where electric potential is null. I solved the ...
0
votes
2answers
183 views

A little question about Gauss' Law

So I've just learned Gauss' Law a few days ago. I also worked out some applications of Gauss' Law. But I have a little confusion. In a couple of books that I referred, I found a statement that I don't ...
2
votes
4answers
1k views

Electric Field due to a disk of charge. (Problem in derivation)

This might be a really silly question, but I don't understand it. In finding the electric field due to a thin disk of charge, we use the known result of the field due to a ring of charge and then ...
1
vote
2answers
1k views

Gauss’s Law inside the hollow of charged spherical shell

Use Gauss’s Law to prove that the electric field anywhere inside the hollow of a charged spherical shell must be zero. My attempt: $$\int \mathbf{E}\cdot \mathbf{dA} = \frac{q_{net}}{e}$$ $$\int E ...
0
votes
1answer
106 views

Electric Field Homework Question

Can a charged particle move through an electric field that exerts no force on it?
1
vote
0answers
54 views

Where does the potential energy associated with the field go if it is removed? [closed]

I have an electric field and a certain charged particle in it that has a certain potential energy associated with it. Where does the energy go if I remove the field?
2
votes
1answer
73 views

Light Waves and Light Photons gedanken Experiment

Suppose you have a source of light that emits light with a wavelength of 2 meters, and you set the device to be turned on and switched off alternately. You also set it so that each interval the device ...
1
vote
1answer
305 views

How to find the electric field due to a point charge in 3 dimensions?

A point charge with charge $+q$ is situated at $(x,y,z)$. How do I find the electric field at $(p,q,r)$? $E=k\frac{q}{r^2}$, right? So why isn't the electric field, ...
1
vote
2answers
4k views

Field between the plates of a parallel plate capacitor using Gauss's Law

Consider the following parallel plate capacitor made of two plates with equal area $A$ and equal surface charge density $\sigma$: The electric field due to the positive plate is ...
2
votes
2answers
330 views

Does the induced charge on a conductor stay at the surface?

My textbook says that when a conductor is placed in an electric field, the electrons in it realign so that the net electric field inside the conductor is zero. There isn't a proof for this. It merely ...
1
vote
0answers
265 views

Charge distribution inside a parallel plate capacitor [closed]

I'm having difficulty deriving a known expression for the magnitude of the Electric Field within a parallel plate capacitor with applied potential difference $V$ and an immobile charge distribution ...
8
votes
3answers
2k views

Electric Field inside a regular polygon with corner charges

If we have equal charges located at the corners of a regular polygon, then the electric field at its center is zero. Are there other points inside a polygon where the field vanishes? The simplest ...
4
votes
2answers
526 views

Electric field in a sphere with a cylindrical hole drilled through it

Suppose that you have a sphere of radius $R$ and uniform charge density $\rho$; a cylindrical hole with radius $a$ ($a\ll R$) is drilled through the center of the sphere, leaving it like a "necklace ...
3
votes
1answer
72 views

Does it really make sense to talk about field lines?

Field lines should only provide a visual representation of a field. There is a rule for their construction: take an object subject to a field, move it by d$\mathbf{r}$ and draw the direction of the ...
0
votes
0answers
23 views

What's the proof that the polarization occur s to the electric field of the light? [duplicate]

What's the proof of the light polarization that it happens to the electric field and not the magnetic field? How did Malus discover that the light is polarized although he didn't see the waves ...
3
votes
2answers
829 views

Why doesn't the magnetic field polarize when polarizing light?

If the magnetic field doesn't polarize does it follow the electric field path of propagation? or does it vanish?
0
votes
0answers
33 views

Is this expression of electric field correct?

I know that the electric field component of electromagnetic wave should be written as the first equation shown, but some times it can be expressed in terms of complex amplitude of electric field as in ...
1
vote
2answers
211 views

Interaction energy between dipole and potential

It is known that interaction energy = $-\vec{p}.\vec{E}$ where $\vec{p}$ is dipole moment and $\vec{E}$ is the electric field. I have to calculate the interaction energy of a system whose dipole ...
1
vote
2answers
702 views

How electromagnetic fields travel through vacuum?

How electromagnetic fields travel through vacuum is it right to say that they propagate or travel? do they alternately form each other by charged particles?
1
vote
1answer
118 views

What is the outcome of a changing Magnetic Field?

The question might sound elementary. However, the thing is this. Changing Magnetic field produces a changing electric field. That changing electric field would produce a changing magnetic field. So, ...
8
votes
7answers
10k views

Why can two (or more) electric field lines never cross?

The the title is self explanatory, I guess. Why can two (or more) electric field lines never cross?
2
votes
2answers
629 views

Does field line concept explain electric field due to dipole?

Consider an electric dipole consisting of charges $-q$ and $+q$, separated by a distance $2a$ and placed in free space. Let $P$ be point on the line joining the two charges (axial line) at a distance ...
9
votes
9answers
5k views

Why can't electrostatic field lines form closed loops?

My physics textbook says "Electrostatic field lines do not form closed loops. This is a consequence of the conservative nature of electric field." But I can't quite understand this. Can anyone ...
1
vote
0answers
48 views

charged oil drop in electric field [closed]

I am currently doing coursework for my A2 physics course. I am dropping a charged oil drop in a horizontal electric field and I was wondering how to calculate how much the droplet would deviate given ...
5
votes
1answer
155 views

Poynting theorem and entering power

I refer to the time-domain version of the Poyinting theorem in electro-magnetism: $- \displaystyle \oint_S (\mathbf{E} \times \mathbf{H}) \cdot d\mathbf{S} - \int_V \mathbf{E} \cdot \mathbf{J}_i \ dV ...
1
vote
1answer
279 views

Field from non-conducting plate?

For a non-conducting sheet, the electric field is given by: $$E = \frac{\sigma}{2\epsilon_0}$$ where $\sigma$ is the surface charge density. This equation holds well for a finite ...
1
vote
1answer
86 views

Electric field near surface of a conductor? [duplicate]

If the electric field on a positive charge is non-zero, then the charge accelerates in the direction of the field. The field at the surface of a conductor is perpendicular to the surface. Why ...
1
vote
2answers
601 views

Calculating the electric potential in cylindrical coordinates from constant E-field

I am having so much trouble with this problem. I feel like I shouldn't be, but I am. A uniform electric field, $\vec{E} = E_0\hat{x}$. What is the potential, expressed using cylindrical ...
2
votes
3answers
136 views

Calculating the Potential from the E-Field

I find that often times I'll be tripped up by questioning whether or not I can do something mathematically, and be unable to come up with a satisfying answer. This is, unfortunately, one of those ...
2
votes
1answer
306 views

What does the electric field caused by a charged cylinder look like?

I am talking about a cylinder with a large enough radius:length ration that it cannot just be treated as a line. I would think that the electric field lines come out the curved and flat surfaces ...
2
votes
1answer
192 views

How can electrons move along the conductive wire? ( seems to be a paradox )

Tangential components of the electric field across an interface between two media, with no impressed magnetic current densities along the boundary of the interface, are continuous. So: $ n \times (E_2 ...
6
votes
2answers
147 views

Quantization of electrostatic $\vec E$ field?

Can a electrostatic field $\vec E=\vec E(x,y,z)$ (time-independent) or electrostatic potential $\phi=\phi(x,y,z)$ be quantized? If yes, will these quanta be photons again? But we don't have an ...
3
votes
0answers
125 views

Electric field of a capacitor in dielectric medium with weird size

I have been learning gauss's law in capacitor recently, recently I come up with this problem that I couldn't solve myself. If we have a capacitor,and a dielectric medium with half the volume between ...
1
vote
0answers
138 views

Electric field produced by a charged ring

I have a question I couldn't find an answer for anywhere. There is a ring of radius $R$ which is charged uniformly with linear density $\lambda$, and I have to find the electric field on any point of ...
0
votes
2answers
2k views

What is meant by “net charge”?

Lets consider a system of two opposite charges separated by a certain distance (dipole), if we ask what is the net charge for this system? the answer would be zero. The net charge (what I have come ...
-1
votes
1answer
78 views

Electric Potential Energy

When work is done on a positive test charge by an external force to move it from one location to another, does the potential energy increases or decreases, and does the electric potential increases or ...