Cathode motion). It is continued externally by electrons moving into the battery which constitutes positive current flowing outwards. For example, the Daniell galvanic cell's copper electrode is the positive terminal and the cathode. A battery that is recharging or an electrolytic cell performing electrolysis has its cathode as the negative terminal, from which current exits the device and returns to the external generator as charge enters the battery/ cell. For example, reversing the current direction in a Daniell galvanic cell converts it into an electrolytic cell where the copper electrode is the positive terminal and also the anode. In a diode,
Standard electrode potential is sufficient to calculate either one of the potentials. Therefore, standard electrode potential is commonly written as standard reduction potential. The electrode potential cannot be obtained empirically. The galvanic cell potential results from a "pair" of electrodes. Thus, only one empirical value is available in a pair of electrodes and it is not possible to determine the value for each electrode in the pair using the empirically obtained galvanic cell potential. A reference electrode, standard hydrogen electrode (SHE), for which the potential is "defined" or agreed upon by convention, needed to be established. In this case SHE is set to