Question

Yellow light emitted from a sodium lamp has a wavelength (λ) of 580 nm. Calculate the frequency (ν) and wave number (v) of the yellow light.

Answer 1

From the expression,

λ=c/v

we get,

v=c/λ

Where, ν = frequency of yellow light

c = velocity of light in vacuum = 3 × 10⁸ m/s
λ = wavelength of yellow light = 580 nm = 580 × 10^–9 m
Substituting the values in expression (i):

v=3*10⁸/580*10^-9=5.17*10¹⁴ s^-1

Thus, frequency of yellow light emitted from the sodium lamp = 5.17 × 1014 s^–1
Wave number of yellow light v=1/λ

1/580*10^-9=1.72*10⁶ m^-1