Electrostatics: Charged Energy & Beyond

[Sunny Singh]

I am learning in Electrostatics that the work done to construct a charge configuration is ∑qV and when we assume that charge is not discrete but continuous we get the work done to be ∫E.Edv and hence we say that the energy stored in electrostatic field is ∫E.Edv. when applying this formula to point charges we find that the energy of a point charge becomes infinite (i don't know what to make of it). In the same way magnetostatic energy is ∫B.Bdv . So electromagnetic energy is basically the work done to make the charge configuration.My question is suppose there is no charge around but only EM field like in the case of light . Here too i can use the above formula to find energy but as there is no charge configuration and hence no energy supplied to make the charge configuration, from where do this energy comes in the field?

 

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I am learning in Electrostatics that the work done to construct a charge configuration is ∑qV and when we assume that charge is not discrete but continuous we get the work done to be ∫E.Edv and hence we say that the energy stored in electrostatic field is ∫E.Edv. when applying this formula to point charges we find that the energy of a point charge becomes infinite (i don't know what to make of it). In the same way magnetostatic energy is ∫B.Bdv . So electromagnetic energy is basically the work done to make the charge configuration.My question is suppose there is no charge around but only EM field like in the case of light . Here too i can use the above formula to find energy but as there is no charge configuration and hence no energy supplied to make the charge configuration, from where do this energy comes in the field?

First of all, electric field must be generated from some charge, near or far it is from the point you evaluate the field. Secondly, you don't need to know what generated that field: a region of space where a field is present has energy by itself, and mass too.

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