Electromechanical power flowcharts in systems of electrical circuits
  We present an original undergraduate level compilation for the physics of electromechanical systems with special attention to power flow. An approach based on energy considerations is presented that is specially suited to compute the mechanical and electrical actions of electromagnetic fields and to draw power flowcharts that clarify the path taken by energy in typical devices. The procedure guarantees energy conservation and provides a consistent way for auditing the power flow. 
J. M. Diaz de la Cruz
physics.ed-ph