All Questions
18
questions
4
votes
0
answers
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)...
0
votes
2
answers
286
views
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
votes
0
answers
54
views
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 ...
- 49
1
vote
1
answer
89
views
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 ...
- 23
0
votes
2
answers
438
views
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 ...
3
votes
4
answers
282
views
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
views
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
1
vote
2
answers
277
views
Does an infinite wire of charge have an infinite potential energy per unit length?
I was doing a physics problem in Purcell's E&M book when I encountered a problem that asked to find the work needed per unit length to assemble an infinite wire charge of radius $a$, by bringing ...
- 23
1
vote
5
answers
273
views
Where is energy in energy density?
I was learning about energy density and it seemed to be defined as the potential energy per unit volume in an electric field
$\frac{dU}{dV} = \frac{1}{2}\epsilon E^2$
But how can just the electric ...
- 59
0
votes
1
answer
314
views
Which is the difference between electrostatic potential energy and electrostatic potential stored energy?
here it's written that:
The electrostatic potential energy, $U_E$, of one point charge $q$ at position $r$ in the presence of a point charge $Q$, taking an infinite separation between the charges as ...
- 1,319
1
vote
2
answers
80
views
How to make sense out of Potential Energy?
My teacher says that Energy is in the form of Electric field. I've also seen the mathematical prove. (The amount of work done in bringing a charge from infinity to that point in the Electric Field) ...
- 63
2
votes
4
answers
491
views
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 ...
0
votes
2
answers
32
views
Proof for $W_{\text{total}}$
Looking upon a certain solution of a problem in Griffiths regarding the work done in arranging two concentric spheres with inner shell having charge $q$ and outer shell with charge $-q$ and I found a ...
- 213
1
vote
1
answer
246
views
Question regarding electrostatic potential energy [duplicate]
I was calculating potential energy due to point charge at origin using relationship
$$U=\dfrac{1}{2}\epsilon_{0}\displaystyle\int \mathbf {\vec E.\vec E\ } \ d\tau$$
and it comes out to be infinity ...
user182868
15
votes
2
answers
5k
views
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 ...
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