Question

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

Answer 1

(i) The frequency of the light wave is

$\frac{1}{period}=\frac{1}{2.0\times {10}^{-10}s}=5\times {10}^9/s$.

(ii) The wavelength of light wave is

$\frac{c}{\nu }=\frac{3\times {10}^{8}m/s}{5\times {10}^9/s}=6.0\times {10}^{-2}m$.

(iii) The wave number of light wave is

$\overline{\nu }=\frac{1}{\lambda }=\frac{1}{6.0\times {10}^{-2}}=16.66/m$.