All Questions
9
questions
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1
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222
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How should I interpret these integrals from Griffiths 'Intro to Electrodynamics'?
The book defines the electric field at a point $P$ a distance $r$ due to a point charge $q$ as:
$$ E = \frac{1}{4\pi \epsilon _0} \frac{q}{r^2}$$
it then tells us that the electric field at a point $P$...
- 345
0
votes
1
answer
358
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How is this possible (electric field integral)?
In the electric field subject, $dq$ is ok to integral. How is this possible? $Q$ is not even changing variable. Can you explain its math?
$$E=k\int \frac{dq}{r^2}.$$
- 13
1
vote
1
answer
546
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Taylor expansion of charge density in Jackson's book
I am learning from Jackson (3r edition), where I found one concept very confusing, that is Taylor expansion of charge density. (This is given in section "1.7 Poisson and Laplace equations" p....
- 131
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4
answers
4k
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I don't understand the logic/concept of $\mathrm dQ=\lambda\,\mathrm dx$. How did we arrive at this expression?
So I've been learning Electrostatics. So while solving for the Electric Field Due to an infinite positively charged rod, I encountered the following expression on the internet wherein the following ...
0
votes
2
answers
498
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Why is charge density dependent on distance?
If we suppose that we want to find the electric field at some point P. Let's consider a small volume element $ \Delta V_i$ , which contains an amount of charge $\Delta q_i$. The distance between ...
- 1
1
vote
1
answer
781
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Energy of continious charge distribution
In the book of Griffith intro to electrodynamics, on page 94, the energy of continuous charge distribution is derived in the following way:
W(total energy) = $\frac{1}{2} \int\rho V d\tau$, where $\...
- 367
2
votes
1
answer
949
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Electric field at any point due to a continuous charge distribution
I am reading Purcell and Morin's Electricity and Magnetism 3rd Edition.
Equation ($1.22$):
$$\vec{E}(x,y,z)=\dfrac{1}{4 \pi \epsilon_0}
\int \dfrac{ρ\ (x^\prime, y^\prime, z^\prime)\ \hat{r}\ dx^\...
- 91
1
vote
3
answers
398
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How to mathematically prove that point charge and infinitesimal volume charge are same?
In electrostatics, while deriving certain elementary equations, I have seen all the books just assuming that point charge and infinitesimal volume charge are same.
How can we rigorously, ...
- 91
4
votes
1
answer
2k
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Description of charged sphere with Heaviside function in cylindrical coordinates
I need to describe density of charge of uniformly charged sphere (radius R, total charge Q, position of centre (0,0,0)) with Dirac delta function and Heaviside step function. The hard part is to ...
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