( ( ( The speed ) ( of light ) ) ( ( ( is ( dependent ( of ( ( ( ( the medium ) ( ( through which ) ( it passes ) ) ) and ) ( ( the change ) ( in ( velocity ( of light ) ) ) ) ) ) ) ) ( as ( it ( ( passes ( from ( ( one medium ) ( to ( another causes ) ) ) ) ) ( ( the phenomenon ) ( of refraction ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN speed)) (PP (IN of) (NP (NN light)))) (VP (VBZ is) (ADJP (JJ dependent) (PP (IN of) (NP (NP (NP (DT the) (NN medium)) (SBAR (WHPP (IN through) (WHNP (WDT which))) (S (NP (PRP it)) (VP (VBZ passes))))) (CC and) (NP (NP (DT the) (NN change)) (PP (IN in) (NP (NP (NN velocity)) (PP (IN of) (NP (NN light))))))))) (SBAR (IN as) (S (NP (PRP it)) (VP (VBZ passes) (PP (IN from) (NP (NP (CD one) (NN medium)) (PP (TO to) (NP (DT another) (NNS causes))))) (NP (NP (DT the) (NN phenomenon)) (PP (IN of) (NP (NN refraction)))))))) (. .)))
The speed of light is dependent of the medium through which it passes and the change in velocity of light as it passes from one medium to another causes the phenomenon of refraction .
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NN light)) (VP (VBZ passes) (PP (IN from) (NP (CD one) (NN medium))) (PP (TO to) (NP (DT another)))))) (, ,) (NP (PRP it)) (VP (VBZ changes) (NP (NN speed))) (. .)))