What is a wave number ?Explain with full details along with the series in spectrum of hydrogen.

Asked by  | 10th Jul, 2011, 12:00: AM

Expert Answer:

Wave number is defined as the number of wavelengths per centimetre and is equal to the inverse of wavelength expressed in centimetre. It is dented by and is expressed in cm-1.  A wavenumber can be converted into quantum-mechanical energy E in J or regular frequency ? in Hz according to


Note that here wavenumber and the speed of light are in cgs units, so care must be taken when doing these calculations.

For example, the wavenumbers of the emissions lines of hydrogen atoms are given by

where R is the Rydberg constant and ni and nf are the principal quantum numbers of the initial and final levels, respectively (ni is greater than nf for emission).

Answered by  | 11th Jul, 2011, 10:27: AM

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