物理同chem ge電流

The direction of electric current is defined in terms of the direction of flow of positive charges, i.e. the same direction as electric field lines. Hence, if the charge carriers are positive, e.g. +ve ions, protons, positrons... etc, their direction of flow will be the same as the defined direction of electric current. On the other hand, if the charge carriers are negative, e.g. electron, -ve ions ... etc., their direction of flow is opposite to that of the defined current.