( Voltage ( ( expresses ( ( the amount ) ( of ( energy ( expended ( per ( amount ( of ( electric charge ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Voltage)) (VP (VBZ expresses) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (NN energy)) (VP (VBN expended) (PP (IN per) (NP (NP (NN amount)) (PP (IN of) (NP (JJ electric) (NN charge)))))))))) (. .)))
Voltage expresses the amount of energy expended per amount of electric charge.
(ROOT (S (NP (NNP Voltage)) (VP (VP (VBZ is) (RB not) (NP (NP (DT the) (JJ same)) (PP (IN as) (NP (NN energy))))) (, ,) (CC but) (VP (VBZ means) (NP (NP (DT the) (NN energy)) (PP (IN per) (NP (NN unit) (NN charge)))))) (. .)))