( ( ( Attraction ( between ( ( the ( open core ) ) ( of ( ( ( an ( electromagnetic solenoid ) ) and ) ( a piece ) ) ) ) ) ) ( of ( ( iron or ) ( a magnet ) ) ) ) . )
(ROOT (NP (NP (NNP Attraction)) (PP (IN between) (NP (NP (DT the) (JJ open) (NN core)) (PP (IN of) (NP (NP (DT an) (JJ electromagnetic) (NN solenoid)) (CC and) (NP (DT a) (NN piece)))))) (PP (IN of) (NP (NP (NN iron)) (CC or) (NP (DT a) (NN magnet)))) (. .)))
Attraction between the open core of an electromagnetic solenoid and a piece of iron or a magnet.
(ROOT (S (NP (DT An) (NN electormagnet)) (VP (VBZ is) (NP (NP (DT a) (NN piece)) (PP (IN of) (NP (NP (NN iron)) (PP (IN inside) (NP (DT a) (NN solenoid))))))) (. .)))