# Multipole expansion

consider a charge distribution say q, 2q, 3q, kept on the vertices of an equilateral triangle. There exist monopole, dipole ,qudrupole etc terms in the potential expression. these 3 charges are neither dipoles nor quadrupoles.why does the potential contains terms due to dipole and quadrupole then?

• A multipole expansion can result from the expansion of the $\frac{1}{|x-x^{'}|}$. It's similar to a Taylor series expansion of $\frac{1}{|x-x^{'}|}$ But you need to show us the equation in question and indicate where the potential is being evaluated before anyone can help you. – Cinaed Simson Nov 5 at 19:54