Question

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

Answer 1

(i)Frequency, = c/λ

1 nm = 10^-9 m 

580 nm = 580 × 10⁻⁹m 

= 580 × 10⁻⁷ cm

v= \(\frac{3.0 \times10^8ms^ {−1}}{580 \times10^{−9}m}\)

= 5.17 × 10¹⁴ s ⁻¹

(ii) Wave number, 

v̅ = 1/ λ

= \(\frac{1}{580 \times10^{−7}cm}\) 

1.724 × 10⁴ cm⁻¹