All Questions
129
questions
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Principle of superposition in spherical shells
If I have a spherical shell with a uniform positive charge desnity on its surface is near a positive point charge q (sitting in quadrant II area)
In consideration of the electric field strength and ...
- 33
0
votes
1
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125
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Capacitor with a spring [closed]
The plates of capacitor are attached with non conducting spring of spring constant k. The initial separation between the plates is d and the spring is relaxed initially. Now the charges +Q and -Q is ...
0
votes
1
answer
49
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Decreasing energy but at expanse of what
question : A hollow spherical shell with radius R has charge Q uniformly distributed
over it.
(i) show that the energy
stored in this system is $\dfrac{Q^2}{8\pi \epsilon_{0}R}.$
(ii) Now imagine ...
user182868
3
votes
1
answer
446
views
Field at the center of a cube with positively and negatively charged faces [duplicate]
I'd like to share an interesting physics problem with the Physics SE community, one I found in a Russian Physics Olympiad Paper (without solution)
An insulating hollow cube of edge length $L$ has ...
- 1,921
2
votes
1
answer
2k
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Potential due to a charged ring : Electric field discontinuity
I have just begun with my third year intermediate course in electrodynamics. A standard problem in electrostatics that one may repeatedly encounter is that of finding the potential due to a uniformly ...
- 380
6
votes
3
answers
1k
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Physics olympiad question about a charge capacitor
This is problem 1463 from the Russian magazine Quant.
Unfortunately my Russian is not good enough, so I apologize if the translation of the problem contains errors.
Problem. Inside a flat charge ...
- 417
0
votes
1
answer
56
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Energy formula electric field
I am currently reading through my electrodynamics lecture notes and I can't understand a calculation.
$$ E = \frac{1}{2} \int \mathrm{d}^3x \, \phi(\mathbf{x}) \rho(\mathbf{x}) = - \frac{\epsilon_0}{...
user164828
0
votes
2
answers
125
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Electron deflection in a strong electric field thought experiment
I'm learning the basics of electromagnetism, and something that seems trivial as an exercise is proving confusing. Here is an excerpt:
$1a)$ An electron moves initially vertically into a region of ...
- 3,200
3
votes
1
answer
1k
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Field of a cylinder with surface charge density $\sigma= \sigma_0 \cos(\theta)$
I have this problem, where I have a cylinder with the surface charge density in the title. The angle $\theta$ refers to the angle on the horizontal axis. We had seen a similar exercise with spheres, ...
- 165
1
vote
2
answers
2k
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Does a permanent magnet attract a positively charged rod?
I thought that because the charge on the rod is static, there wouldn't be an interaction with the magnetic field, however the answer to the question states that both poles of the magnet would attract ...
- 38
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votes
1
answer
396
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The charge density $\rho_{\infty}$ of the sphere
I have two charged hemispheres (which are very close to each other, we
consider them now as a sphere) with the charge density given as $\rho
= \frac {Q}{\pi a^3 \frac {4}{3+n}} (\frac{r}{a})^n$, ...
user156350
4
votes
1
answer
5k
views
Electric field on a spherical shell with a disk cut out
I came across this problem in Electricity and Magnetism by E.M. Purcell:
A spherical shell of radius $a$ is charged with a uniform surface charge density $\sigma$. A small hole of radius $b <<...
- 301
1
vote
1
answer
447
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A conductive sphere with holes and a charge in them is grounded, from the potential calculation i get the charges have opposite signs?
This is a conductive sphere with two holes in it, they put charge $q_{a}$ in one of the holes and $q_{b}$ in the other hole
(The holes are surronded by conductive material and not open to the outside)....
- 151
0
votes
1
answer
123
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Determining magnetic intensity of tube with variable current density
I'm having the following problem:
Given tube with outer radius of $R_2$ and inner radius of $R_1$ there is electrical current, with density given by $j(r) = j_0 r$. Using Amperes law determine ...
2
votes
1
answer
4k
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Image dipole in front of a conducting grounded plane
In front of an indefinite conducting plane connected to ground and at a distance $d$ of it we locate an electric dipole with dipolar moment $\textbf{p}$ parallel to the plane. What electric field acts ...
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