( ( ( approximate wavelength ) ( of ( visible light ) ) ) ; )
(ROOT (NP (NP (JJ approximate) (NN wavelength)) (PP (IN of) (NP (JJ visible) (NN light))) (: ;)))
approximate wavelength of visible light;
(ROOT (S (NP (JJ Exact) (NN wavelength)) (VP (VBZ determines) (NP (NP (DT the) (NN color)) (PP (IN of) (NP (JJ visible) (NN light))))) (. .)))