Question

What is the shortest wavelength present in the Paschen series of spectral lines?

Answer 1

Rydberg’s formula is given as:

` "hc"/lambda = 21.76 xx 10^(-19) [1/"n"_1^2 - 1/"n"_2^2]`

Where,

h = Planck’s constant = 6.6 × 10⁻³⁴ Js

c = Speed of light = 3 × 10⁸ m/s

(n₁ and n₂ are integers)

The shortest wavelength present in the Paschen series of the spectral lines is given for values n₁ = 3 and n₂ = ∞.

`"hc"/lambda = 21.76 xx 10^(-19) [1/(3)^2 - 1/(∞)^2]`

`lambda = (6.6 xx 10^(-34) xx 3 xx 10^8 xx 9)/(21.76 xx 10^(-19)`

= 8.189 × 10⁻⁷ m

= 818.9 nm