'Returns wavenumber of the wave.
Examples
>>> from sympy import symbols
>>> from sympy.physics.optics import TWave
>>> A, phi, f = symbols(\'A, phi, f\')
>>> w = TWave(A, f, phi)
>>> w.wavenumber
pi*second*f*n/(149896229*meter)'

@property
def wavenumber(self):

    return ((2 * pi) / self.wavelength)
