Sentence:  The <WSD>energy</WSD> received by the `` pill '' causes the resonant circuit to `` ring '' on after the burst and this `` ringing '' takes place at the resonant frequency of the `` pill '' . 
Meaning of the word marked with <WSD> tags:  (physics) a thermodynamic quantity equivalent to the capacity of a physical system to do work; the units of energy are joules or ergs