Question

Calculate the wavelength, frequency and wave number of a light wave whose period is 2.0 × ${10}^{–10}$ s.

Answer 1

Frequency (ν) of light = $\frac{1}{Period}$
$\frac{1}{2.0\times {10}^{-10}s}=5.0\times {10}^9{s}^{-1}$
Wavelength (λ) of light = $\frac{c}{v}$
Where,
c = velocity of light in vacuum = 3×${10}^8$ m/s
Substituting the value in the given expression of λ:
$\lambda =\frac{3\times {10}^8}{5.0\times {10}^9}=6.0\times {10}^{-2}$
Wave number ( $\overline{v}$ ) of light
$\frac{1}{\lambda }=\frac{1}{6.0\times {10}^{-2}}=1.66\times {10}^1{m}^{-1}=16.66m^{-1}$