All Questions
Tagged with electric-fields potential-energy
27
questions
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 ...
- 492
4
votes
2
answers
4k
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Is there really no meaning in potential energy and potential?
I have been told all my physics life that potential energy between two mass/charge has no meaning and only their difference has meaning. The same goes for electric potential, only the difference ...
- 937
5
votes
4
answers
1k
views
Electrical potential energy stored in vacumm for a single point charge?
I have come to know the electrostatic potential energy in vacuum is given by
$${\frac{1}{2}} \epsilon_0\int d^3x {E^2} $$ and this energy is due to the mutual electrostatic coulomb potential energy.
...
- 1,336
6
votes
4
answers
169k
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Relation between Electric field and potential
I am unable to understand from this - sign comes. Which step I have done wrong?
- 135
3
votes
3
answers
4k
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Electrostatic energy integral for point charges
The electric energy stored in a system of two point charges $Q_1$ and $Q_2$ is simply $$W = \frac{1}{4\pi\epsilon_0}\frac{Q_1Q_2}{a}$$ where $a$ is the distance between them.
However, the total ...
- 519
2
votes
4
answers
491
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How can we have negative work in electrostatics, if $W=(\epsilon_0/2)\int\! E^2\ \mathrm{d}\tau$?
This question is motivated by Section 3.2.3 in Griffiths.
Therein, we are considering the force of attraction between a point charge and an infinite conducting plane. One can calculate the field ...
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:
$$\vec E= \vec E_f+\vec E_b$$
$$\phi=\phi_f+\phi_b$$
$$\vec D=\vec E+\vec P$$
$$\rho=\...
1
vote
1
answer
8k
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Why does the electric potential for an infinite line charge seem to have to be worked out from negative infinity rather than positive infinity?
The electric field of an infinite line charge in the plane perpendicular to the line charge can be given as:
$$E=\frac{1}{2\pi \epsilon r}$$
Where $r$ is the perpendicular distance from the line.
...
- 176
0
votes
2
answers
11k
views
Work done in moving a charge
So, recently while I was studying electric fields and charges for a test, I came across the definition of electric potential as -
The amount of work done in moving a unit positive test charge from ...
- 947
15
votes
2
answers
5k
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How is energy stored in magnetic and electric fields?
We say that there is energy associated with electric and magnetic fields. For example, in the case of an inductor, we give a vague answer saying that an energy of $\frac{1}{2} LI^2$ is stored in the ...
- 7,203
12
votes
8
answers
3k
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Why is the electrostatic force felt in straight lines?
When two positive charges are kept close, they get repelled in the direction of a line joining both the charges. Why is it so?
Also, why is the repulsion in a straight path?
In both the cases, the ...
- 662
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 ...
- 6,102
4
votes
5
answers
1k
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Electric potential and electric potential energy definitions
I was thinking about the definition of this 2 concepts and I don't know if I understand exactly what they mean.
Electric potential is just the work that must be done to bring a charge from infinity to ...
- 73
4
votes
2
answers
24k
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When work done is taken negative in electrostatics?
Let us say a point charge Q was moved across a potential difference V, then work done would be : QV.
This work is taken negative when done external agent, Please explain when It is negative and ...
3
votes
3
answers
5k
views
Why is there a minus in the definition of the electric potential?
We usually say that the work done by a force is $\mathrm{d}W = F\cdot\mathrm{d}l$, and the electric potential is $\mathrm{d}U = -E \cdot \mathrm{d}l$). Why do we put a negative sign over there? Is it ...
