We have a formulae to find energy contained by an EM wave, which finds energy per unit volume. Also says it is equally distributed between E and B fields. How do we find EM energy for an EM wave of 50Hz in a copper wire? Because it is low frequency, instead of space we guide by conducting copper wire. I want to know how it relates to energy formulae for EM wave in space. I know we can find it by Vrms and Irms but that is more on application side, easy way. Thanks in advance.