Emission transitions in the Paschen series end at orbit n=3 and start from orbit n and can be represented as v=`3.29xx10^(15)(Hz)[1//3^(2)-1//n^(2)]`. Calculate the value of n if the transition is observed at 1285 nm. Find the region of the spectrum.

Explanation

`v=(c)/(lamda)=(3.0xx10^(8)m*s^(-1))/(1285xx10^(-9)m)=3.29xx10^(15)((1)/(3^(2))-(1)/(n^(2)))`
r, `2.33xx10^(14)=3.29xx10^(15)((1)/(9)-(1)/(n^(2)))`
or, `(2.33xx10^(14))/(3.29xx10^(15))=(1)/(9)-(1)/(n^(2)) or, 0.071=(1)/(9)-(1)/(n^(2))`
or, `(1)/(n^(2))=(1)/(9)-0.071 or, (1)/(n^(2))=0.040 or, n^(2)=25`
or, `n=5`. therefore, radiation corresponding to 1285 nm belongs to the infrared region.