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

The wavelength of yellow light is 580 nm = 580 × 10⁻⁹ m.
The frequency of yellow light, ν = c/λ = (3.0 × 10⁸ m/s) / (580 × 10⁻⁹ m) = 5.17 × 10¹⁴/s.
The wave number of yellow light, ṽ = 1/λ = 1 / (580 × 10⁻⁹ m) = 1.72 × 10⁶/m.