For electromagnetic radiation, the wavenumber is related to the wavelength by:

1. Wavenumber counts how many waves fit into unit length. 2. So it is simply the reciprocal of the wavelength: $\bar{\nu}=\dfrac{1}{\lambda}$. 3. Frequency is a different quantity, given by $\nu=\dfrac{c}{\lambda}$. 4. Energy links to frequency through $E=h\nu$, and so to wavelength through $E=\dfrac{hc}{\lambda}$. 5. Giving similarities between the wave parameters rather than these mathematical relationships was the recorded error. _Source: NECTA ACSEE 2023 Chemistry 132/1, Question 4: The Atom_