( ( Spherical waves ) ( ( ( ( emerge ( behind ( the ( two slits ) ) ) ) and ) ( create ( an ( interference pattern ) ) ) ) . ) )
(ROOT (S (NP (JJ Spherical) (NNS waves)) (VP (VP (VB emerge) (PP (IN behind) (NP (DT the) (CD two) (NNS slits)))) (CC and) (VP (VB create) (NP (DT an) (NN interference) (NN pattern)))) (. .)))
Spherical waves emerge behind the two slits and create an interference pattern.
(ROOT (S (NP (JJ Constructive) (NN interference)) (VP (VBZ is) (SBAR (WHADVP (WRB when)) (S (NP (CD two) (NNS waves)) (VP (VBP combine) (S (VP (TO to) (VP (VB create) (NP (DT a) (JJR larger) (NN wave))))))))) (. .)))