Login

 why is coulombs law applicable only to point charges?

Coulombs law is valid for a point charge because when we come across the formula we find it is the force given between two bodies kept at a distance r. Now if we keep an extended by which is not a point, we cannot uniquely give the distance r.

Let’s see this by an example, let’s taken an extended charged object of charge Q and try to find the force due to this object and a point charge q.

We see we cannot take a single unique distance r to make it fit into Coulomb’s law. Therefore Coulomb’s law is not applicable in this case.

  • 6
View Full Answer

Coulomb's law is applied to point charges because there are "problems" applying it to a charge that has "dimension" to it. A charge is surrounded by an electric field. If we cannot treat it as a point, then the charge has to be "distributed" through the "body" of the charge. It will change the way we have to do the math.

If we view charges as non-point sources, then we can't apply the mathematics to the charges in quite the same way as we do when we work things out with point sources. Take a charge that isn't a point source and one that is. If the charge that isn't a point source has "dimension" to it, then the charge on that charge (if that makes sense) is not eminating from a point but from the "body" of the charge as a whole. The electric field will be "distributed" over the volume of the body of the charge, and its effect on a point source will have to be worked out differently than it would if it was point source-to-point source

 gud luck :))

  • 1
What are you looking for?