Question

What is the shortest wavelength present in the Paschen series ofspectral lines?

Answer 1

The shortest wavelength in Paschen series of the spectral lines is given for n 1 =3 and n 2 =∞.

The shortest wavelength can be calculated using Rydberg’s formula.

hc λ =21.76× 10 −19 [ 1 ( n 1 ) 2 − 1 ( n 2 ) 2 ]

Where, Planck’s constant is h, speed of light is cand n 1 , n 2 are integers.

By substituting the given values in above equation, we get

hc λ =21.67× 10 −19 [ 1 3 2 − 1 ∞ 2 ] λ= 6.6× 10 −34 ×3× 10 8 ×9 21.76× 10 −19 λ=8.189× 10 −7  m =818.9 nm

Thus, the shortest wavelength in Paschen series is 818.9 nm.