( ( As ( ( ( alternating ( current moves ) ) ( ( back and ) forth ) ) ( in ( a wire ) ) ) ) ( , ( ( magnetic fields ) ( ( are ( created ( around ( the wire ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN As) (S (VP (VBG alternating) (NP (JJ current) (NNS moves)) (ADVP (RB back) (CC and) (RB forth)) (PP (IN in) (NP (DT a) (NN wire)))))) (, ,) (NP (JJ magnetic) (NNS fields)) (VP (VBP are) (VP (VBN created) (PP (IN around) (NP (DT the) (NN wire))))) (. .)))
As alternating current moves back and forth in a wire, magnetic fields are created around the wire.
(ROOT (S (NP (NNP Alternative) (JJ current)) (VP (VBZ is) (VP (VBN produced) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (NN magnet) (CC or) (NN coil)) (VP (VBZ moves) (ADVP (RB back) (CC and) (RB forth)) (ADVP (RB repeatedly))))))) (. .)))