question_answer 74)

Emission transitions in the Paschen series end at an orbit of \[n=3\] and start from orbit n and can be represented as, \[v=3.29\times {{10}^{15}}Hz\left[ \frac{1}{{{3}^{2}}}-\frac{1}{{{n}^{2}}} \right]\] Calculate the value of 'n' if the transition is observed at 1285 nm. Find the region of the spectrum.

Answer:

Frequency, \[v=\frac{c}{\lambda }\] \[3.29\times {{10}^{15}}\left[ \frac{1}{{{3}^{2}}}-\frac{1}{{{n}^{2}}} \right]=\frac{3\times {{10}^{8}}}{1285\times {{10}^{-9}}}\] On solving, \[n=5\] The radiation corresponding to \[n=5\] to \[n=3\] will lie in the infrared region.