Can Point Charges Be Used to Approximate Charged Bodies?

[sahilmm15]

"If the sizes of charged bodies are very small as compared to the distances between them, we treat them as point charges". Can you explain me the statement. And what does "sizes of charged bodies" refer here. Thanks

 

[Ibix]

The electric field of a charged cube, for example, is different from a charged tetrahedron. Very far from the object, though, the differences are negligible, and the difference from the field of a point charge is negligible. So we can just treat it as a point charge and save ourselves from some nasty integrals.

The size of the body, in this context, isn't really precisely defined, since we're talking about an approximation. It's something like the largest distance there is across the object. You need to be much further away than that.

 

[sahilmm15]

The electric field of a charged cube, for example, is different from a charged tetrahedron. Very far from the object, though, the differences are negligible, and the difference from the field of a point charge is negligible. So we can just treat it as a point charge and save ourselves from some nasty integrals.

The size of the body, in this context, isn't really precisely defined, since we're talking about an approximation. It's something like the largest distance there is across the object. You need to be much further away than that.

Thanks for the reply. I appreciate it.