而呢第2個postulate 其實已經限制咗有咩value嘅angular momentum is allowed,呢個情況我哋會話angular momentum is quantized. 一個important consequence of quantization of angular momentum就係佢導致一個quantized嘅energy level,個derivation自己睇返書。本textbook應該有show比你睇點prove energy level of hydrogen atom,應該會用到L=mvr=nh/(2pi).
而quantization of energy level亦都解釋咗點解會有一個line spectrum,而唔係一個continuous spectrum. 因為energy level唔係continuous,而係quantized嘅,得某啲energy level is allowed. 所以得某啲energy 嘅light佢先absorb到,而呢個energy必須 = energy level嘅 difference in a hydrogen atom。