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0 votes
2 answers
110 views

Convergence of the infinite series $\sum_{n\in\text{odd}}^{\infty}\frac{z^n}{n}$

This is a follow-up on a previous question I have asked, but since I have made some improvements, I wanted to make a new post. I was studying 'Introduction to Electromagnetism' by David Griffiths and ...
Rasmus Andersen's user avatar
1 vote
0 answers
59 views

Kramers-Kronig computation for real susceptibility

i am trying to get the real part of electric susceptibility using the imaginary part with Kramers-Kronig relation for a Lorentz-Drude model.I chose to ask this question in math stack exchange as im ...
zero's user avatar
  • 11
4 votes
5 answers
216 views

How to calculate $\int_0^{2\pi}\frac{\cos(\phi)-R}{1-2R\cos(\phi)+R^2}\cos(n\phi)~d\phi$?

I wish to calculate $$I(R)=\int_0^{2\pi}\frac{\cos(\phi)-R}{1-2R\cos(\phi)+R^2}~\cos(n\phi)~d\phi,$$ where $n\in\mathbb{N}$, $R\in[0,1)$. Based on trial and error from plugging numbers into Wolfram ...
Peanutlex's user avatar
  • 1,027
1 vote
1 answer
89 views

How to calculate the leading order solution to $\sum_{n=-\infty}^\infty\frac{1}{[(x+n\epsilon)^2+1]^{3/2}}$?

I wish to calculate a series solution to the following sum, $$S(x)=\sum_{n=-\infty}^\infty\frac{1}{[(x+n\epsilon)^2+1]^{3/2}},$$ where $x$, $\epsilon$ $\in$ $\mathbb{R}$ and $\epsilon \ll 1$. Do you ...
Peanutlex's user avatar
  • 1,027
0 votes
1 answer
45 views

Perpendicular complex-valued vectors

I'm reading an E&M Textbook and somewhat confused about how to find perpendicular vectors that satisfy the right hand rule, when the coefficients are complex. For example, if $E$ has direction $(\...
IAmTheWalrus's user avatar
4 votes
0 answers
128 views

How to solve $\sum_{n=-\infty}^\infty\frac{y^2}{[(x-n\pi)^2+y^2]^{3/2}}$?

I need to solve this sum: $$\sum_{n=-\infty}^\infty\frac{y^2}{[(x-n\pi)^2+y^2]^{3/2}}.$$ Do you have any ideas for how I could do this? I know that this sum: $$\sum_{n=-\infty}^\infty\frac{y}{(x-n\pi)^...
Peanutlex's user avatar
  • 1,027
1 vote
1 answer
153 views

Variable separation method for solving wave equation

In variable separable method we assume the solution to be the product of such functions each of which is function of only one variable. What is the basis for that assumption? What allows us to assume ...
Sai Krishna Garlapati's user avatar
0 votes
1 answer
249 views

Author's derivation of time-independent form of Maxwell's equations

Laser Electronics, 3rd edition, by Joseph T. Verdeyen, gives the following: To describe an electromagnetic wave, we need two field-intensity vectors, $\mathbf{e}$ and $\mathbf{h}$, which are related ...
The Pointer's user avatar
  • 4,322
0 votes
1 answer
96 views

How to integrate Fresnel Integrals? $\int_0^y e^\frac{-j\beta(z)^2}\rho dz$

I am having trouble solving this integration of a spherical fresnel zone with radius y $\displaystyle\int_0^y e^\frac{-j\beta(z)^2}\rho dz$ , where j is complex and $\beta$ and $\rho$ are constants. ...
It'sJohnny's user avatar
0 votes
0 answers
43 views

Complex Electric Flux Integral

I am working through Gamelin and am having trouble understanding the following: The electric field is given by $\textbf{E} = \frac{1}{r} e_r$ where $e_r$ is the unit radial vector. Through each ...
Emilio Minichiello's user avatar