( ( An electroscope ) ( ( is ( ( a device ) ( that ( will ( detect ( ( ( very small ) charges ) ( of ( static electricity ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT An) (NN electroscope)) (VP (VBZ is) (NP (NP (DT a) (NN device)) (SBAR (WHNP (WDT that)) (S (VP (MD will) (VP (VB detect) (NP (NP (ADJP (RB very) (JJ small)) (NNS charges)) (PP (IN of) (NP (JJ static) (NN electricity)))))))))) (. .)))
An electroscope is a device that will detect very             small charges of static electricity.
(ROOT (S (NP (DT A) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN electroscope)) (VP (VBZ is) (VP (VBN used) (S (VP (TO to) (VP (VB study) (NP (NN charge))))))) (. .)))