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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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Electromagnetsm, isospin, spin-1/2, and the early years of quantum mechanics question

An electron going around in a circular orbit produces a magnetic field because there is a varying electric field. But the electric field of the electron itself is a spherically symmetrical field. ...
questing-monkey's user avatar
0 votes
0 answers
23 views

What's the difference between electrical induction and chemical batteries [closed]

I'm new in physics/chemistry and i'd like to know what's the difference between both of them and how do they affect the electromagnetic field and move electrons. Also I'd like to know how does a ...
Psi's user avatar
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0 votes
1 answer
62 views

Electric field experienced by a charge

We have two charges, say $Q_1$ and $Q_2$. The magnitude of the electric field $E$ experienced by charge $Q_2$ is: $$E = \frac{k Q_1}{r^2}$$ where $k$ is Coulomb's constant and $r$ is the distance ...
user134613's user avatar
0 votes
0 answers
28 views

Can field effect transistor s channel s varying depletion layers generate electric flux and control output current indirectly

Since magnetic field lines without need of contact attracts iron filing and drag them closer so that magnetic field line remain smallest.same analogy applied to field effect transistor ions in the ...
Phoenix Bird Eduventures's user avatar
0 votes
3 answers
32 views

Electric field at a point due to dielectric inserted in between a parallel plate capacitor [closed]

Here, I have a parallel plate capacitor with each plate having surface charge density $\sigma$. A dielectric of dielectric constant $K$, is inserted partially between the two plates. What would be the ...
NPC's user avatar
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0 votes
1 answer
33 views

Understanding Symmetries and Invariances in Electrostatic Fields [closed]

I'm currently studying electrostatics and I'm having trouble understanding the concepts of symmetries and invariances of electrostatic fields. I understand the basic definitions of symmetry planes and ...
Boulahya Kaouthar's user avatar
2 votes
0 answers
49 views

Potential of circle and $n$-gon

Consider power central fields $f \sim r^k, - \infty < k < \infty$, and unit circle, "charged" in the sense of the field. We will be interested in the potential within the circle, i.e. ...
lesobrod's user avatar
  • 163
0 votes
1 answer
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Why electric field increase near the cable connected in AC 220V socket even current is zero?

If I put low frequency electric field meter near the connected cable in AC 220V socket, he show 1200 V/m even if device is turn OFF(zero current), if disconnect cable from socket, field drop to 8 V/m. ...
22flower's user avatar
  • 613
0 votes
6 answers
117 views

How will the capacitance of a capacitor reduce when the distance between the plates is increased?

Now I know that if the potential difference between the plates increase that capacitance will reduce, but for that also I thought as the distance between the plates increases, the electric field ...
Leisha Lakhotia's user avatar
0 votes
1 answer
62 views

Understanding dielectrics on the basis of induced charge and energy density

Simply, why is the energy density in a dielectric medium = $\frac{1}{2} K \epsilon_o E^2$? For a simple case such as that of a capacitor with a dielectric medium inside it, to find the magnitude of ...
Kayen Jain's user avatar
2 votes
1 answer
63 views

Does the geometric shape of the cross-section of an infinitesimally thin conducting charged thread (wire) affect its electric field?

Assume that a solid conducting torus (toroidal ring), with a cross-section of a circle of (minor) radius $r$, is negatively charged. Solving Poisson's equation, we can find the charge distribution of ...
Mohammad Javanshiry's user avatar
0 votes
4 answers
44 views

Comparing Electric Potential Energy of two Charges

I do not know what I am missing here and would appreciate a little help in figuring out the flaw in my logic. I have a row of positive charges and a row of negative charges as shown in the image above....
Zeiglar's user avatar
2 votes
2 answers
94 views

Electric force is zero in a solenoid

This is a question from Young and Freedman's University Physics. The book's answer says that the electric forces are zero because the wire is electrically neutral, with as much positive charge as ...
nomadicmathematician's user avatar
0 votes
3 answers
64 views

$z$-component of electric field due to a static square loop

I am having trouble finding the $z$-component of an electric field discussed in problem 2.4 of Griffith’s introduction to electrodynamics. Suppose we have a square loop of side length $a$ carrying a ...
Joa's user avatar
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1 answer
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Using an imaginary conducting shell of infinite radius to calculate capacitance of a spherical conductor

This is a statement from Serway's Modern Physics which I don't understand. It tries to explain capaticance for a single conductor. Imagine a single spherical charged conductor. The electric field ...
nomadicmathematician's user avatar
0 votes
3 answers
100 views

What is the net macroscopic electric field at any point inside a dielectric?

This question is based on section 4.2.3 of Introduction to Electrodynamics by David J. Griffiths (Third Edition). Consider a point $\vec{r}$ inside a dielectric where we are interested in finding the ...
Solidification's user avatar
3 votes
3 answers
145 views

Electric Field Within a Conductor

I was reading Purcell’s text on electrodynamics when I read his argument that in the absence of external forces, there cannot be any electric fields within a conductor for the static situation. My ...
V T Naveen Mugundh's user avatar
2 votes
1 answer
89 views

Confusion on the definition of dielectric permittivity

I don't understand how we're defining the dielectric permittivity, sometimes it's defined as the ability of the material to resist the electric field and sometimes as the ability to permit the ...
Manish Parmar's user avatar
-1 votes
0 answers
50 views

In which direction are the photons of an accelerated electron emitted? [duplicate]

It concerns the case described below (from this question): I assume that it is possible to set up a double-slit experiment where the particles, say electrons, are accelerated from when they leave the ...
HolgerFiedler's user avatar
1 vote
2 answers
64 views

Why is the electric potential from a positive sphere not negative? [duplicate]

Say we have a positive point charge located somewhere. Then the electric field due to this point charge is $\vec{E} = \frac{1}{4\pi \epsilon_0}\frac{Q}{r^2}\hat{r} $ , now considering potential is $V =...
J. Doe's user avatar
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2 votes
2 answers
227 views

Dipoles as vectors

A triatomic molecule $X_2Y$ has plane structure as shown in figure. Due to difference in electronegativity, charge acquired by each X atom is $q$ and charge on Y atom is $- 2q$. The bond length ...
Anshu Gupta's user avatar
1 vote
2 answers
159 views

Does cutting out the surfaces with no surface charge affect the charge distribution on the remaining parts of a conducting surface of arbitrary shape?

Assume that we have an arbitrary conducting surface being charged positively/negatively. Also, assume that we have extracted charge distribution by solving the Poisson's equation with proper boundary ...
Mohammad Javanshiry's user avatar
1 vote
0 answers
47 views

Total charge within a sphere

Consider an electric field in free space with $$ \mathbf {D} = -3z\mathbf {a_r} μCb/m^2 $$ I need to calculate the total charge within a 3mm sphere centered at (0,1,1). I calculate the charge ...
Pavlos Papanikolaou's user avatar
0 votes
1 answer
43 views

Surface charge density within a parallel plate capacitor on different voltages

I need a way to vary the surface charge density without changing the electric field. My idea is to use two large conducting parallel plates close to each other in vacuum enclosed in a grounded vessel (...
Sibo's user avatar
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1 vote
2 answers
84 views

Divergence of Electric Field of Point Charge is always zero [closed]

I might have a bug in my brain, but I just can't figure this out. Please help. According to the first of the Maxwell Equations, we have $$ \nabla\cdot\vec{E}=\frac{\rho}{\epsilon_0}. $$ And we have ...
tobi-v's user avatar
  • 13
0 votes
1 answer
47 views

What happens when both magnetic field and electric field is applied to a charged particle?

Now what exactly happens when magnetic field and electric field is applied perpendicularly? What happens when they are not perpendicular? In the question, it says that a magnetic field and electric ...
android's user avatar
  • 91
0 votes
0 answers
35 views

Question about electric field around charge density

Suppose the region $0 < x < d$ has charge density $-p$, and the region $-d < x < 0$ has charge density $p$. Why is electric field on the edge of region in point d zero? If negatively ...
Kopun Vukašin's user avatar
1 vote
1 answer
24 views

Metallic bonds in Copper and Electric field application

Didnt know where to put this since its like a combination of Chemistry and Physics. But in the picture below, we can see that they've defined a metallic bond as essentially the attraction between the ...
Wander verse's user avatar
2 votes
2 answers
109 views

Confusion with treatment of unit vectors in electrostatics

I am reading Griffiths’ Introduction to Electodynamics and there are two problems where the methodology for treating unit vectors in integrals seems inconsistent to me. When we are trying to find the ...
Joa's user avatar
  • 179
1 vote
1 answer
23 views

Electric field at any point in the region between two capacitors is proportional to the magnitude of charge on each conductor

This is a statement from Young and Freedman's University Physics Section 24.1 on Capacitors. Suppose we have any two conductors with charges $-Q$ and $+Q$ on each charged with a battery. Then this ...
nomadicmathematician's user avatar
2 votes
1 answer
40 views

Bound Charges in Polarized Material

I'm currently working my way through chapter 4 of Griffith's Introduction to Electrodynamics (4th ed) and I ran into an issue with his notation. In chapter 4 sectin two, when calculating the electric ...
ReggiePlasmaQs's user avatar
3 votes
3 answers
184 views

Is it valid to write $\int{dq}$?

While I was going through the expression for the electric field in continuous charge distributions (Section 2.1.4) in Griffiths' textbook, it was given as $${E(r)} = \frac{1}{4\pi\epsilon_o}\int{\...
Sahil Muhammed's user avatar
2 votes
0 answers
73 views

Induced charge on conducting sphere sliced by a plane

We are given a conducting solid sphere, and it is cut by a plane as shown. A charge $Q$ is given to the smaller part of the conductor, and it is required to find the induced charge on the surface of ...
Eisenstein's user avatar
0 votes
3 answers
108 views

When an electron is moving at relativistic speeds, is the electric field length-contracted as well?

Suppose I have an electron that is moving at relativistic speeds. SR says some degree of length contraction should take place. Does this mean that the electric field around the electron should also be ...
Mike Battaglia's user avatar
1 vote
2 answers
66 views

Potential of an electric dipole

I'm currently working my way through Griffith's Introduction to Electrodynamics (4th ed). In chapter 3 section 4, he shows that we can take the equation for the electric potential of a continuous ...
ReggiePlasmaQs's user avatar
0 votes
1 answer
45 views

Uniqueness of charge distribution in conductor

I found out about a result describing the uniqueness of the charge distribution on a conductor. It says that for a given total charge on a conductor and a given charge distribution of the outside (...
FundamentalTheorem's user avatar
6 votes
1 answer
190 views

Accumulated charge in conductors

Conductors placed in electric fields undergo a redistribution of charges. There is a separation of charges which occurs only on the surface. But what prevents the charge from leaving the surface of ...
Users's user avatar
  • 426
0 votes
0 answers
32 views

How is the local field in a dielectric material calculated?

I have read in different sources (text, video, amongst others) that the local field in a dielectric material placed within a capacitor can be easily calculated as the sum of 4 electric fields: $E_{...
user7077252's user avatar
1 vote
1 answer
76 views

Potential on conducting shell without image charge

Edit 2: I know how image charges work. But I'm still trying to rationalize without it. Edit 1: scrap this, realized what I needed was image charges. This entire question is sort of a jury-rig ...
zxayn's user avatar
  • 73
0 votes
1 answer
68 views

A General Analysis of Charge Distribution inside conductors

I'll go ahead and present my question straight-forward and then talk about the calculation details.My Question is: how do you define a conductor in Electrostatics? What are the basic(minimum) set of ...
Charu _Bamble's user avatar
0 votes
3 answers
151 views

I am basically having doubt about where Lorentz transformation is being applied?

I was solving example 12.14 in Griffiths' Introduction to Electrodynamics) The question was: A point charge $q$ is at rest at the origin in system $S_{0}.$ What is the electric fieldof this same ...
nbkhdbkhbkndjdjbj's user avatar
0 votes
3 answers
91 views

Induced charges due to uniform electric field

Suppose there is a finite metallic conductor placed in a uniform electric field. Will the magnitude of positive or negative charge induced on it depend on its shape or will it only depend on the ...
Gautam's user avatar
  • 47
7 votes
7 answers
4k views

Is it impossible to construct a Faraday cage that can block a *static* electric field?

I think the answer is yes. My reasoning is this: Imagine for argument's sake, we could have a charged negative source that has its field blocked by a Faraday cage. We can transport a positive charge ...
KDP's user avatar
  • 6,102
0 votes
1 answer
161 views

Intensity and complex electric field

I have come across an issue with the use of complex electric and magnetic fields that I just cannot quite figure out. I will lay out my thought-process and I would like to know if and why it is wrong. ...
Hervé Schmit-Veiler's user avatar
0 votes
0 answers
37 views

Equipotential surface of Hemispherical charge distribution

I was attempting a question of electrostatics from the book Pathfinder for Olympiads and Jee advanced Physics. In a solution of certain question, the base of a uniform hemispherical charge ...
Navanieeth TS's user avatar
2 votes
1 answer
69 views

To ensure that there is no $E$-field inside the superconductor and Faraday's law holds true the surface current seems to eliminate its cause, why?

In a Faraday's induced EMF experiment with a superconducting loop, the current at the surface of the superconducting loop creates a magnetic field that nullifies the magnetic field created by the Bar-...
SURYABARTA SAHA's user avatar
0 votes
1 answer
38 views

Why do multiply electric field by the area? [closed]

I have a question about why we multiply e field by the surface area. When finding the total of something in a given area we need to take how much there is in one unit and multiply it by the area. If i ...
crazyfoo's user avatar
1 vote
3 answers
80 views

Work done in a moving conducting bar and in a Faraday disk

I deeply apologize for my ignorance, but I am asking this since I still can't seem to grasp what my teachers relayed to me a few days ago about two exercises that I solved in an intrinsically wrong ...
Some random guy's user avatar
0 votes
1 answer
53 views

Confusion regarding a statement regarding conductors [duplicate]

While discussing conductors, our lecturer told us that, UNDER ELECTROSTATIC CONDITIONS, electric field is zero in the "meat" of the conductor. Using this assumption (and using Gauss law), ...
Ayanokouji Kiyotaka's user avatar
1 vote
0 answers
16 views

Why is the intensity of a beam of light the squared magnitude of the phasor and not just the squared magnitude of the real part?

I'm learning about phasors and light intensity and there are two conflicting things I've been told that I can't reconcile. Firstly I've been told that a phasor $e^{-ikz+i\phi}$ is a mathematical way ...
Hadi Khan's user avatar
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