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