Question

the wavelength range of visible spectrum ranges from V 450 nm to R 750 nm. Express these wavelength in frequency. Give 1 nm = 10^-9. Find the wave number.

Answer 1

$$\begin{gathered} Frequency=\frac{speedoflight}{wavelength} \\ \nu =\frac{c}{\lambda } \\ Wavenumber=\frac{1}{\lambda } \\ 1.)Wavelength=450nm \\ Frequency=\frac{3\times {10}^8}{450\times {10}^{-9}}=6.67\times {10}^{14}{s}^{-1} \\ Wavenumber=\frac{1}{450\times {10}^{-9}}=2.22\times {10}^6{m}^{-1} \\ 2.)Wavelength=750nm \\ Frequency=\frac{3\times {10}^8}{750\times {10}^{-9}}=3.992\times {10}^{14}{s}^{-1} \\ Wavenumber=\frac{1}{750\times {10}^{-9}}=1.33\times {10}^6{m}^{-1} \end{gathered}$$