Question

Find the ratio of longest to shortest wavelength in Paschen series.
(Ans : 2.286:1 )

Answer 1

the ratio of longest to shortest wavelength in Paschen series.

1. Paschen Series accounts for transition of electron to n=3 level.

2. Now we know the for wavelength radiated in transition is given by:

1/(lambda)=R*Z²*{(1/nf²)-(1/ni²)}

where R is Rydberg Constant and Z is the atomic no. and nf and ni are the final and initial state of electron in stationary orbits.

3. For shortest wavelength nf=3 and ni=inf

4. For longest wavelength nf=3 and ni= 4

5. Putting these value in above formula and getting the ratio of smallest and longest wavelength we get,

{Lambda longest}/{lambda shortest}=16:7=2.286:1