Brushing up on my understanding of electrodynamics, using Griffiths Introduction to Electrodynamics(4th ed), I'm always questioning the magnitude of "energy" required/consumed in the process of doing work "against" back emf.
The work you must do against the back emf to get he current going, this is a fixed amount, and it's recoverable: you get it back when the current is turned off.
$$\frac{\ d {W}}{dt} =-{\varepsilon I }= L I\frac{\ d {I}}{dt}$$
From $I$ = $0$ to a final value of $I$ the work done is now :
$$W = \frac{1}{2}LI^2$$
---- Griffiths Introduction to Electrodynamics(4th ed) Pg.328
It seems if we consider energy to be the "budget" of how much work can be done in a system, the majority of that "budget" is used to do work against back emf, since the energy lost due to heat can be reduced greatly, and the energy required to move charges( i/.e current $I$) is negligible, in addition, the emphasis of Lenz law in relation to Faraday's law, all points to that observation.
The work done to change the flux $\phi$ in such system, is the highest in magnitude and uses most of that "budget", I did an analysis on a problem, applying the conservation of energy, deriving it using Maxwell's equations(3&4) and Newton's laws as well.
I also attempted to model the system using Poynting's theorem, the observation is the same, most of the "work" or energy transferred is towards doing work against back emf to change the state of an electrodynamics system( $\Delta \phi$).
1) Is that a fair observation?
2) Is there a "Reason" besides the experimental fact, as to why the majority of work done or energy consumed is for back emf?
