i will TRY to give a COMPLETELY MATHEMATICAL solution so that no one can oppose it by logic :P
let us try to derive ohm's law...given in many books i suppose
let vd is the drift velcity and Γ be the average relaxation time(time between two consequetive collision of the electron) for the conductor V be the potential difference and i the current flowing through the conductor(suppose a cylinder of length L and area of cross section A).
so we get, E=VL [E=electric field.]
so, Fe=qE=eVL [Fe=force experienced by electron; e=charge on electron; m=mass of an electron.]
so, ae=eVmL
we get, vd=aΓ=eVΓmL
also i=neA(vd) [i am too lazy to prove this now :(]
so, i=ne2VΓmL
so, Vi=mLne2Γ
now, R=0 implies, Γ=∞
this implies that nothing will be present to stop the electron from accelerating.
thus the electron accelerates through an electric field.
now this enlightened on me when i was revising atomic structures all over again.
why did we reject rutherford's atomic model?
it is because according to that model electron was getting accelerated in presence of an electric field and according to laws of electrodynamics a charge accelerating in presence of an electric field loses electromagetic radiations and thus the electron spirals into the nucleus.
thus similarly in our case of sperconductor (and L=0) i.e purely capacitive circuits, the energy is lost by electromagnetic radiations.
i know Sonne had already pointed this out but at that time i was not as such convinced because of the reason he gave i.e. he wrote in my chatbox that the electromagnetic radiation come as the electrons are promoted to higher energy levels and rebounded back!!
donno if it is correct!
now the rest 12CV2 is indeed lost as electromagnetic radiation but that is not due to change in energy levels but due to acceleration of electron in an existing electric field.
now i do not know the reason why the electron loses the energy when it is accelerated in an existing electric field. only what i know is that it is according to a law of electrodynamics and that it got historically applied to reject rutherford's atomic model and so i am using it again!
SO THE THREAD IS STILL ALIVE WITH A NEW QUESTION!!
why does an electron lose energy when t is accelerated in an electric field??