Answer
1875.6 nm
Work Step by Step
1
The least energetic spectral Line for Hydrogen in the infra red range can be obtained when an Electron in H atom jumps from Level 3 to Level 4.
Now,
Rydberg's Equation is given as :
1/ λ = R [1/(n1)² - 1/(n2)²]
Where,
λ : Wavelength
R : Rydberg's Constant = 1.0967 x 10^7 / m
2
Solution :
Here,
n1 = 3
n2 = 4
Substituting the values in the Rydberg's formula,
1/ λ = R [1/(3)² - 1/(4)²]
1/ λ = 1.0967 x 10^7 x [1/9 - 1/16]
1/ λ = 1.0967 x 10^7 x (7/144)
λ = 1875.6 x 10^-9 m
λ = 1875.6 nm
