Wavenumber Wavenumber In the physical sciences, the wavenumber (also wave number or repetency) is the spatial frequency of a wave, measured in cycles per unit distance or radians per unit distance. Whereas temporal frequency can be thought of as the number of waves per unit time, wavenumber is the number of waves per unit distance. In multidimensional systems, the wavenumber is the magnitude of the wave vector. The space of wave vectors is called reciprocal space. Wave numbers and wave vectors play an essential role in optics and the physics of wave scattering, such as X-ray diffraction, neutron diffraction, and elementary
Oh Dear! What Can the Matter Be? basin it was the same water the next washed her face in – and nobody knew they were there. </poem> "Seven Old Ladies" was not the first parody, however. Long before that parody, the song had been parodied for political purposes. One such parody can be found in the "Wisconsin State Journal" of 1 March 1864. It was written to exhort parents, who during the U.S. Civil War had not taken much interest in public schooling in Madison, to visit the schools of their children. Its lyrics were: <poem> Oh, dear, what can the matter be? Oh, dear, what can