Tagged Questions
0
votes
1answer
91 views
Electric field around charged cylinder
This is a homework question, so please don't give me the answer outright. I just need help conceptually.
"A cylindrical shell of length 190 m and radius 4 cm carries a uniform surface charge density ...
1
vote
2answers
134 views
Electric lines of force
Why cant electric lines of force pass through the charged sphere? Well, basically that's how a Faraday cage works, but how can it be so?
1
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3answers
192 views
Why can we use Gauss' law to compute electric field?
For simplicity I'm considering only the sphere case.
In the Gauss' Law formulation we have some field E introduced by charges $Q$ inside some sphere, then we compute flux and integrate, and we get ...
1
vote
1answer
415 views
Electric field inside and outside a metallic hollow sphere
1) It is known that inside a metallic hollow sphere it will not experience outside electric field because of the charge separation of electrons and holes at the surface of sphere and creating an equal ...
0
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1answer
168 views
2
votes
1answer
980 views
Electric field due to a solid sphere of charge
I have been trying to understand the last step of this derivation. Consider a sphere made up of charge $+q$. Let $R$ be the radius of the sphere and $O$, its center.
A point $P$ lies inside the ...
1
vote
1answer
321 views
Divergence of non conservative electric field
I'm looking for the proof that the 1st Maxwell equation is valid also on non conservative electric field.
When we are talking about a electrostatic field, the equation is ok. We can apply the Gauss ...
5
votes
5answers
445 views
Paradox with Gauss' law when space is uniformly charged everywhere
Consider that space is uniformly charged everywhere, i.e., filled with a uniform charge distribution, $\rho$, everywhere.
By symmetry, the electric field is zero everywhere. (If I take any point in ...
1
vote
1answer
162 views
What is discontinuity in Vector Fields
I am reading David J. Griffiths and have a problem understanding the concept of discontinuity for E-field.
The E-field has apparently to components. (How does he decompose the vector field into the ...
1
vote
2answers
159 views
In which cases is it better to use Gauss' law?
I could, for example calculate the electric field near a charged rod of infinite length using the classic definition of the electric field, and integrating the: $$
\overrightarrow{dE} = \frac{dq}{4 ...
2
votes
2answers
561 views
Electric potential of sphere
(a) I am a little confused about this part. The point at A to B isn't radial. The electric field is radially outward, but if I look at the integral
$$\int_{a}^{b}\mathbf{E}\cdot d\mathbf{s} = ...
0
votes
2answers
3k views
Using Gauss's Law to calculate electric fields between plates
I have two earthed metal plates, separated by a distance $d$ with a plane of charge density $\sigma$ placed a distance $a$ from the lower plate. I want to derive expressions for the strength of the ...
1
vote
2answers
448 views
A closed surface, no charge enclosed, yet flux not 0?
!
The book says it is $E_0\pi r^2$ because the flux through the circle is equal to the curved part of the paraboloid.
I don't understand this, shouldn't the total flux be 0 for the whole surface? ...
3
votes
1answer
2k views
Why we cannot use Gauss's Law to find the Electric Field of a finite-length charged wire?
One of my physics books has a nice example on how to use Gauss's Law to find the electric field of a long (infinite) charged wire. However, at the very end of the example, the author ends by saying ...
0
votes
2answers
294 views
Electric fields in/around conductors
So according to my notes, the field inside a conductor is zero. But what, exactly, is meant by inside?
I think we are in electrostatics for the purpose of this question.
The reason it is zero is ...
4
votes
3answers
960 views
“Find the net force the southern hemisphere of a uniformly charged sphere exerts on the northern hemisphere”
This is Griffiths, Introduction to Electrodynamics, 2.43, if you have the book.
The problem states Find the net force that the southern hemisphere of a uniformly charged sphere exerts on the ...
5
votes
3answers
806 views
Charge Distribution on a Parallel Plate Capacitor
If a parallel plate capacitor is formed by placing two infinite grounded conducting sheets, one at potential $V_1$ and another at $V_2$, a distance $d$ away from each other, then the charge on either ...
3
votes
1answer
95 views
Scaling of Static Electric Field
The electric field of a point charge goes like $\displaystyle\frac{1}{r^2}$
The electric field of an infinite line goes like $\displaystyle\frac{1}{s}$
The electric field of an infinite plane is ...
1
vote
1answer
269 views
Electric Flux Density - Ring Charge
A ring placed along $y^{2}$ + $z^{2}$ = 4, x = 0 carries a uniform charge of 5 $\mu$C/m. Find D at P(3,0,0)
Should I be using Gauss's Law to solve this problem? I was considering using a spherical ...
2
votes
3answers
199 views
Gauss' law - changes in the magnitude of E field inside the closed surface
Gauss's law says that the flux through a closed surface which contains neither a sink nor a source will be zero.
It's quite clear that all field lines will have to exit somehow, but the
strength of ...
-2
votes
1answer
4k views
Electric field due to nonconducting plastic sheets [closed]
Two very large, nonconducting plastic sheets, each 10.0 cm thick, carry uniform charge densities $\sigma_1, \sigma_2, \sigma_3$ and $\sigma_4$ on their surfaces (the four surfaces are in the ...
2
votes
2answers
313 views
Gauss' law giving zero field where field is not zero?
Two plastic sheets with charged densities as shown:
I'm trying to find the field at $B$. I obtained the correct answer by adding up the fields created by each charge density. But I realized that ...
