The equation gives the dynamic relation between {TAIL ~ the voltage U} at and the power P through {HEAD ~ a connection} to the load 
The equation gives the dynamic relation between { TAIL ~ the voltage U } at and the power P through { HEAD ~ a connection } to the load
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH