Does anyone know what the laws of conservation are when dealing with resistors?

Well, I guess you can vaguely state if you have, for example, 2 resistors in series: then, in accordance with the law of conservation of energy, the voltage drop across each resistor (the energy used by each resistor) add up to the voltage (energy) supplied by the source.
This is only thin that really comes to mind. Whadya think?