def conductivity_to_imaginary_permittivity(freq: float,
                                           conductivity: float) -> float:
    """Converts between conductivity and imaginary permittivity

    This is a simple and straightforward conversion between the value
    of conductivity, in S/m, and the imaginary part of the complex
    relative permittivity, at a particular frequency.

    Args:
        freq: A `float` with the frequency, in GHz, at which to do the
              conversion
        conductivity: A `float` value for the conductivity in S/m

    Returns:
        The unitless value for the imaginary part of the complex
        relative permittivity.

    Raises:
        ZeroDivisionError: If you specify 0 Hz, i.e. DC, for the frequency
    """

    try:
        imag_permittivity = 17.97591 * conductivity / freq
    except ZeroDivisionError as error:
        raise ZeroDivisionError('Frequency must be > 0'). \
              with_traceback(error.__traceback__)

    return imag_permittivity