This is puzzling to me because I have learnt that a charged sphere has the same electric field and electric potential at a point beyond its surface. So does it mean that a point charge is also inherently a sphere?
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How about the surface areas of the sphere vs the point charge? What does inherently mean? – Kurt G. Aug 08 '23 at 08:20
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Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. – Community Aug 08 '23 at 09:23
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Related: https://physics.stackexchange.com/q/24001/2451 , https://physics.stackexchange.com/q/119732/2451 and links therein. – Qmechanic Aug 08 '23 at 10:06
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We can write any electric field as the sum of the fields from a monopole, a dipole, a quadrupole and so on up to whatever number of higher poles we need. This is known as a multipole expansion. Any we can, mathematically at least, have a point monopole, a point dipole, a point quadrupole, and so on.
However when we use the term point charge we are normally specifically referring to a monopole, and not to any of the higher poles. The monopole field is spherically symmetric so it is the same as the field outside a sphere. However this does not mean a point charge is a tiny sphere. In fact I would put it the other way round - a point charge is a monopole and a charged sphere has the same field as a point charge because it has the same symmetry as the point charge.
Whether point charges actually exist depends on what exactly you mean by point charge. An electron is often described as a point, and that would make it a point charge. However note that the magnetic field of that electron is a point dipole so a point does not have to be a monopole.
John Rennie
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