Why is Coulomb's Law Limited to Point Charges?

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    Coulomb's law Law
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Coulomb's Law is applicable only to point charges because it defines the electrostatic force between two discrete charges, expressed mathematically as F=Kq1q2/r². The law states that this force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. For extended bodies with charge distributions, the law can be approximated by treating them as a collection of point-like charges. This approximation allows for the calculation of forces through summation, but it is a different application rather than a direct use of Coulomb's Law. Therefore, while Coulomb's Law is foundational, its direct application is limited to point charges.
supreabajaj
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Coulomb's Law...

Can anyone please tell me why is Coulomb's Law applicable only to the point charges?
 
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Write down Coulomb's Law. What do the symbols in the equation mean?
 


Statement- The electrostatic force of interaction between any two point charges is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them.


Mathematical Expression- F=Kq1q2/r*r
 


Let us consider an extended body having a charge(known as charge density). We could approximate by assuming that the extended body is made out of many point-like charges(more point like charges=better approximation).

Then consider another charged body(pointlike or non pointlike. for simplification, try point-like). Then, apply Couloumb's law through summation.

Then take the limit and see what happens.
 


supreabajaj said:
Statement- The electrostatic force of interaction between any two point charges is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them.


Mathematical Expression- F=Kq1q2/r*r

There is your answer. Coulomb's Law, the way you have written it, involves two charges and two charges only. But if you know how to write the force between two charges, you can find the force between charge distributions by assembling forces in pairs, but that's not Coulomb's Law, but an application of it.
 
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