def setPhysicalDimension(self, edfsignal, physical_dimension):
        """
        Sets the physical dimension of signal edfsignal ("uV", "BPM", "mA", "Degr.", etc.)

        :param edfsignal: int
        :param physical_dimension: str

        Notes
        -----
        This function is recommended for every signal and can be called only after opening a file in writemode and before the first sample write action.
        """
        if edfsignal < 0 or edfsignal > self.n_channels:
            raise ChannelDoesNotExist(edfsignal)
        self.channels[edfsignal]['dimension'] = physical_dimension
        self.update_header()