All Questions
129
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I’m struggling with this question of gauss law application
I am confused with this question.What Gaussian surface do I take to calculate the electric field at the $q$ charge? Should it be a cylinder containing the whole system? Or should it be a cylindrical ...
- 125
2
votes
2
answers
162
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Any boundary conditions missing from this problem? [closed]
Recently I was solving some boundary value problems in Electrostatics. I stumbled upon a problem with an infinitely long cylinder (axis along the $z$-direction and radius $a$) with a plate inside it (...
- 23
1
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0
answers
95
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Soap bubble with air blown in and charge distributed [closed]
So, I was trying to do this question and here is my attempt:
I first tried work out the surface tension forces like so:
I did $ F= PA$
$ P = 4 \frac{\gamma}{r}$ by laplace law
so,
$ F = 16\gamma \pi ...
- 7,980
0
votes
1
answer
161
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Electron Plasma Frequency
Displayed is the context
My question is, why doesn't the electric field from the electrons permeate throughout the cold plasma?
Surely there will be flux on the RHS of the boundary as there is an ...
- 268
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2
answers
228
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Electric potential infinite box
I have a question about separation of variables to calculate the electric potential.
In the picture below the potential is only on the top of the box, which is infinite in the $z$-direction. What are ...
- 85
1
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2
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55
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Electric field exerted by a ball with varying density
Say there's a ball with radius R. In $0<r<d$, the density is some $\rho_1(r)$ and in $d<r<R$, the density is $\rho_2(r)$. When I calculate the total charge enclosed in $d<r<R$, how ...
- 1,038
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341
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Electric field on the surface of dielectric sphere and outside sphere
Let a dielectric sphere of radius $r_0$ and permittivity $\epsilon_1$ is placed in medium of permittivity $\epsilon_2$. The electric field inside sphere is $\mathbf{E_1(\mathbf{r})} = E_0 \hat{z}$. ...
- 1,335
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1
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343
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Electric field on a point at a height $z$ from the midpoint of a charged line [closed]
First let me say I have already read the thread Electric field a distance z above the midpoint of a straight line segment concerning the exact same problem I'm talking about. Nevertheless, my question ...
- 307
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votes
1
answer
28
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What distance do I use when examining the effect of an electric field on a point outside of a nonconducting sphere with an arbitrary volume charge?
It's easy enough for me to do this for a ring (as I interpret the field lines as "exiting from the centre of the ring") or a point (simply the distance from the point to the other point), but I just ...
- 19
1
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0
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42
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Abstract approach to the total electric force on a charged rod
Suppose we have a 1-dimensional system (x-axis) consisting of rod of finite length $l$ and arbitrary charge density of $\lambda(x)$ at rest extending from the origin to $x=l$. And now, suppose we have ...
- 165
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1
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73
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Electromagnetic waves, displacement currents and capacitors
Question:
Q. A parallel-plate capacitor having plate-area $A$ and plate separation $d$ is joined to a battery of emf $E$ & and internal resistance $R$ at $t=0$. Consider a plane surface of area
...
user220323
0
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2
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228
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Null electric field at infinity? How? [closed]
Suppose there are two charges (4uC each) fixed in the horizontal axis. One is in x=0 and the other in x=8m.
I've obtained the electric field:
$E=-k\cdot4\mu C \cdot [\frac{1}{x^2}+\frac{1}{(x-8m)^2}]...
7
votes
2
answers
784
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Approximating an expression for a potential
In a problem which I was doing, I came across an expression for the potential $V$ of a system as follows $$V = k\left(\frac{1}{l - x} + \frac{1}{l + x}\right)\tag{1}\label{1}$$ where $k$ is a constant,...
- 1,324
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1
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419
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"dielectric constant" or "electrical permittivity"?
What are the differences between "dielectric constant" and "electrical permittivity"?
By searching on the net, I found permittivity = absolute permittivity, which is the measure of capacitance that ...
- 163
0
votes
2
answers
944
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Expressing Maxwell's equations as scalar equations involving differentials in Euclidean space
I am trying to convert Maxwell's equations from the well known differential form (found on Wikipedia Maxwell's equations) into scalar equations involving partial derivatives (more than four equations)....
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