Poynting Theorem: Why is 1st Term Ignored?

[quietrain]

why is it that when we use the poynting theorem to calculate power of

e.g, current flowing down a wire , which gives joule heating ,

we don't make use of the 1st term, but only the 2nd term is used?

doesn't the first term give the total energy stored in the EM fields?

the 2nd term gives the energy flowing out of the EM fields

the 3rd term is the workdone per unit time on the charges right?

 

[vanhees71]

If you look at stationary states only, i.e., if the fields are time independent, the first term vanishes. Otherwise it has to be included.

 

[quietrain]

oh! so as long as i have E or B induction(changing) fields, i have to include the first term because its d/dt is not 0?

thanks!