question_answer

Consider a 3-level system with energies \[{{E}_{1}},{{E}_{2}}\text{ and }{{E}_{3}}\] in ascending order. \[{{\lambda }_{1}},{{\lambda }_{2}}\text{ and }{{\lambda }_{3}}\] are the wavelengths of radiation corresponding to the transitions \[{{E}_{2}}\to {{E}_{1}},{{E}_{3}}\to {{E}_{2}}\text{ and }{{E}_{3}}\to {{E}_{1}}\] respectively. The wavelengths are related by

A)  \[{{\lambda }_{1}}={{\lambda }_{2}}{{\lambda }_{3}}/\left( {{\lambda }_{3}}-{{\lambda }_{2}} \right)\]

B)  \[{{\lambda }_{2}}={{\lambda }_{3}}-{{\lambda }_{1}}\]

C)  \[{{\lambda }_{2}}={{\lambda }_{1}}{{\lambda }_{3}}/\left( {{\lambda }_{1}}+{{\lambda }_{3}} \right)\]

D)