All Questions
Tagged with electric-fields potential-energy
142
questions
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4
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44
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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....
7
votes
7
answers
4k
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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 ...
1
vote
1
answer
82
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Electric potential energy, Electric potential and self-energy of a body
The total work done to bring all the charges constituting a body from infinity to the body one by one is called the electrostatic potential energy of the body. And if I divide the expression of ...
0
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1
answer
30
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Apparent contradiction while calculating potential inside shell due to off center charge
Consider the following scenerio$-$
A point charge $Q$ is placed at an off center point $B$ in a spherical shell made out of a conducting material. We are required to find the potential at the center.
...
4
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0
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58
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Energy in electric field of an electron?
I am just trying to get an intuition for the Griffiths equation no. 2.45, where work done to establish a field E is given by
Say we want to solve it for electric field due to an electron (point-charge)...
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1
answer
96
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Potential energy of an electric dipole without any external field
What is potential energy of an electric dipole without any external field?
If its 0 then why? Wouldn't the charges get attracted thus do work so they must have some potential energy.
-1
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1
answer
39
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Would it be right to say that “Electric Potential” = the potential energy of an individual unit of charge at a certain point in a electric field?
Any replies from people who actually understand the topic (better than me, to say the least lol) and are able to clarify the topic (unlike my teacher), are highly appreciated and encouraged.
2
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4
answers
263
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Electric Potential and Potential Energy
Electric Potential definition is as follows:
Electric potential (also called the electric field potential,
potential drop, the electrostatic potential) is defined as the amount
of work energy needed ...
1
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0
answers
60
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Interpretation of Equation of energy stored in continuous charge distribution [duplicate]
In the book "Introduction to Electrodynamics" by David J. Griffiths, $\boldsymbol\S$ 2.4.3$\blacksquare $ The Energy of a Continuous Charge Distribution, I came across this equation for ...
12
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5
answers
4k
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Why do we say that electric potential energy is stored in the electric field?
I have been learning electrostatics and came across capacitors. I don't really get why do we say energy is stored in electric field rather than in the charges upon which we or the battery does work. I ...
2
votes
1
answer
284
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Energy stored in a space with electric field is $\tfrac12 \varepsilon E^2$ per unit volume. Why?
I'm a high school student and my book says that once it has been established that a region containing electric field $E$ has energy $\tfrac12 \varepsilon E^2$ per unit volume, the result can be used ...
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28
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Electric potential significance [duplicate]
What is the physical significance of electric potential? I know that over dx length of an electric field it varies but let us assume the field to be uniform, how exactly does the potential still ...
1
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1
answer
147
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Confusion pertaining to the electric potential energy
First I'd like to explain why I don't think this question is a duplicate of the many other questions about the electric potential and potential energy. Despite there being many questions and answers ...
0
votes
2
answers
286
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Shouldn't the electric potential energy decrease with separation regardless of whether the charges are positive or negative?
I was revising Electric Fields and it came up that if a positive charge moves in the direction of the electric field (so away from a positive charge), then the electric potential energy will decrease ...
0
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0
answers
54
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Energy in electric field calculated in two different ways
The equation for the energy density in a region of space where there is electric field, $\epsilon_0E^2/2$ implies that energy in the electric field can only be positive. Consider, however, the energy ...
1
vote
1
answer
122
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The (electrostatic) force on an extended object
It is well known that, if I have a system of $N$ particles acted upon only by conservative internal and external forces, then I can obtain the force on the $\mathrm{i^{th}}$ particle as
$$\textbf{F}_i ...
3
votes
1
answer
376
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Coulomb force from a variational principle
See the attached discussion from Zangwill's Modern Electrodynamics, and in particular footnote 9. The point of this question is to understand how to recover Coulomb’s force law from an assumed form ...
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3
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Can electric potential energy be nonzero when the electric field is zero?
I read on wikipedia that electric potential energy of a point charge in the presence of n point charges can be calculated from this formula:
$$
U = k_eq \sum_{i=1}^{n} \frac{Q_i}{r_i}
$$
However, ...
2
votes
0
answers
160
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What should the electrostatic energy of a continuous charge density be?
Hope this doesn't come off as too pedantic or overinterpreted. I've been working on revisiting electrostatic and electrodynamic energy from first principles, and I have the following stumbling block. ...
0
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1
answer
41
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A question on the work done by the electric field? [closed]
It's a well-known fact that the work done by the electric field is given by
$\int -k\frac{{Q(1)Q(2)}}{r^2} dr = \frac{kQ(1)Q(2)}r$
The work being negative as the force and direction of displacement ...
1
vote
1
answer
89
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Energy in electric field of an isolated particle?
I learnt that the energy density of electric field is $\frac{\epsilon_0}2E^2$. However, I'm little confused about how can there be energy associated with an electron in empty space.
How can we have ...
0
votes
2
answers
438
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Distribution of interaction energy in electrostatic systems
If we have two electrostatic systems their interaction energy is given by
$$U=\epsilon_0\int\vec E_1\cdot\vec E_2dV\equiv\int\rho_1\phi_2dV\equiv\int\rho_2\phi_1dV$$ Here the integral is over the ...
1
vote
3
answers
398
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Deriving energy in Dielectrics
Note: I am working in the Lorentz-Heaviside system and all the integrals are over the whole space.
Definitions:
$$\vec E= \vec E_f+\vec E_b$$
$$\phi=\phi_f+\phi_b$$
$$\vec D=\vec E+\vec P$$
$$\rho=\...
0
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1
answer
73
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Disagreements in derivations of electrostatics
In the derivation of the potential energy of electrostatic systems we get (I am working in cgs)
$$W=\frac12\int\phi\,dq=\frac12\iiint\phi\rho\,d V \tag{1}$$ But $$\vec\nabla\cdot\vec E=4\pi\rho$$ Thus
...
3
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4
answers
282
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Consistency of existence of point charges and energy in fields
In Feynman lectures, Volume 2 chapter 8 (https://www.feynmanlectures.caltech.edu/II_08.html#Ch1-audio) at the very end Feynman remarks
We must conclude that the idea of locating the energy in the ...
31
votes
10
answers
8k
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How is energy "stored in an electric field"?
My physics teacher told me the statement "The energy of a capacitor is stored in its electric field".
Now this confuses me a bit. I understand the energy of a capacitor as a result of the ...
4
votes
1
answer
359
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What does negative electrical energy signify?
When we derive the formula for potential energy caused by the torque of a dipole in uniform electrical field we get $U = -pE \cos \theta$. And my textbook tells me that the when the dipole is kept ...
0
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1
answer
155
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Does electric current flow from higher potential to lower potential or from higher potential energy to lower potential energy?
Here, $O$ is a field charge with a $+T$ charge. $A$ and $B$ are test charges with $+T_1$ and $+T_2$ charge, and they are fixed in place. Suppose the points at which $A$ and $B$ are situated are $P_1$ ...
0
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2
answers
411
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Is energy infinite in an electric field?
Energy is defined as the capacity to do work. Work in turn is defined as force x displacement.
An electric field exerts the field in all directions infinitely (even though the strength of that force ...
0
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0
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20
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Using Variation of Energy for a Dielectric to define the Electric Field
I have been reading through Zangwill's Modern Electrodynamics on my own, and I am confused about something in section 6.7.1, concerning the variation of total energy $U$ of a dielectric in the ...