Find the electric potential for an axial quadrupole: point charges q, -2q, q over the z axis at distances l,0,l from the origin. Find the electric potential only for distances r>>l and demonstrate that the potential is proportional to one of the zonal armonics.(adsbygoogle = window.adsbygoogle || []).push({});

Well, I found at wikipedia that an axial multipole has an electric potential given by:

[tex]\Phi(r)=\frac{1}{4\pi \epsilon_0 r}\sum_{k=0}^{\infty}qa^k \left ( \frac{1}{r^{k+1}} \right ) P_k(\cos\theta)[/tex]

But I don't know how to apply this to my problem. I don't know neither what the zonal armonics are.

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# Electric potential for an axial quadrupole

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