Recent content by Mr. Rho

Hi Gregory, thank you for your reply. The solution for me was processing the 4 separate dipoles and then showing that as you say, the problem was that I was trying to plot all the four dipoles at the same time

yes, sorry for that, it is double factorial, thank you for the correction and thank you for those relations you give, the asymptotic limit it's very clear with them! why would wolfram give a wrong relation?

I know that the limit for the spherical bessel function of the first kind when $x<<1$ is: j_{n}(x<<1)=\frac{x^n}{(2n+1)!} I can see this from the formula for $j_{n}(x)$ (taken from wolfram's webpage): j_{n}(x)=2^{n}x^{n}\sum_{k=0}^{\infty}\frac{(-1)^{n}(k+n)!}{k!(2k+2n+1)!}x^{2k} and...

Hi, I'm trying to understand toroidal coordinates, that are a 3D version of bipolar coordinates. Well, I don't understand any of them, already cheked wiki and wolfram sites, but they don't give any clear explanation (in my opinion). Is there a way to get an intuition for obtaining the...

So, I'm trying to plot a 3D "dipole" (an arrow with a small torus around it basically) in mathematica, and want to rotate it according to Euler angles... I use this code for the rotation matrix: rot[a, b, g] := RotationMatrix[g, {1, 0, 0}].RotationMatrix[b, {0, 1, 0}].RotationMatrix[a, {0, 0...

Thank you, I'm studying the multipole expansion of EM fields for such toroidal solenoid but I want to feel confortable with the current density before start to calculate things...

Hi, I'm trying to figure out how the current density for a poloidal current in toroidal solenoid is written. I found you may define a torus by an upper conical ring ##(a<r<b,\theta=\theta_1,\phi)##, a lower conical ring ##(a<r<b,\theta=\theta_2,\phi)##, an inner spherical ring...

I don't know what I was thinking, the correct current density is: \mathbf{J}=I\delta(\theta-\frac{\pi}{2})\frac{\delta(r-a)}{a}\hat{\phi} = I\sin\theta\delta(\cos\theta)\frac{\delta(r-a)}{a}\hat{\phi} it satisfies...

Sorry I wrote the equation wrong, just fixed it. I'm using this kind of spherical coordinates:

Hi, I'm trying to write the current density for such circular loop in spherical coordinates. For a circular loop of radius a that lies in the XY plane at the origin, the current density it's simply: \mathbf{J}= \frac{I}{2\pi\sin\theta}\delta(\theta-\frac{\pi}{2})\frac{\delta(r-a)}{a}\hat{\phi}...

Homework Statement I need to show that \sum\limits_{n=0}^\infty \frac{sin^{4}(\frac{n\pi}{4})}{n^2} = \frac{\pi^{2}}{16} Homework Equations I have this property for odd n \sum\limits_{n=0}^\infty \frac{1}{n^2} = \frac{\pi^{2}}{8} The Attempt at a Solution [/B] I have no idea how to do...

I have that ∇2∅ = 0 everywhere. ∅ is a scalar potential and must be finite everywhere. Why is it that ∅ must be a constant? I'm trying to understand magnetic field B in terms of the Debye potentials: B = Lψ+Lχ+∇∅. I get this from C.G.Gray, Am. J. Phys. 46 (1978) page 169. Here they found that...

Hi people, I have a problem with some integral here. I have a loop of radius a, with a current I = Ioe-iωt' and trying to calculate the radiating fields in the far zone, my procedement is: Current density: J(r',t') = Ioδ(r'-a)δ(θ'-π/2)e-iωt'/2πa2 φ (φ direction) Here t' = t - |r-r'|/c...

Thank you Shyan, that's it, I just found this awesome article that explains in great detail https://www.phy.duke.edu/~rgb/Class/phy319/phy319/node14.html

Hi there, I am reading Chapter 9 of Jackson Classic Electrodynamics 3rd edition, and I don't see why this equality is true, it says "integrating by parts", but I still don't know... any help? http://imageshack.com/a/img673/9201/4WYcXs.png