( ( An ( electrical current ) ) ( ( activates ( ( ( a voice-coil ) ( -LRB- ( ( ( a ( ( solenoid or ) coil ) ) ( of ( wire ( that ( ( gives ( the speaker ) ) ( its voice ) ) ) ) ) ) -RRB- ) ) ) ( that ( acts ( as ( ( an electromagnet ) ( which ( is ( wrapped ( around ( a ( permanent magnet ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT An) (JJ electrical) (NN current)) (VP (VBZ activates) (NP (NP (DT a) (NN voice-coil)) (PRN (-LRB- -LRB-) (NP (NP (DT a) (NN solenoid) (CC or) (NN coil)) (PP (IN of) (NP (NP (NN wire)) (SBAR (WHNP (WDT that)) (S (VP (VBZ gives) (NP (DT the) (NN speaker)) (NP (PRP$ its) (NN voice)))))))) (-RRB- -RRB-)) (SBAR (WHNP (WDT that)) (S (VP (VBZ acts) (PP (IN as) (NP (NP (DT an) (NN electromagnet)) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (VP (VBN wrapped) (PP (IN around) (NP (DT a) (JJ permanent) (NN magnet)))))))))))))) (. .)))
An electrical current activates a voice-coil (a solenoid or coil of wire that gives the speaker its voice) that acts as an electromagnet which is wrapped around a permanent magnet.
(ROOT (S (NP (NP (DT A) (NN solenoid) (CC or) (NN coil)) (VP (VBN wrapped) (PP (IN around) (NP (NN iron) (CC or) (JJ certain) (JJ other) (NNS metals))))) (VP (MD can) (VP (VB form) (NP (DT a) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN electromagnet)))) (. .)))
A solenoid or coil wrapped around iron or certain other metals can form a(n) electromagnet.