Of most concern in a galvanic couple is the intensity of the galvanic action. The amount of current or, more specifically, the current density (current per unit area) determines this intensity. Ohm's law states that the amount of current that can flow is directly proportional to the voltage for any given value of resistance; therefore, galvanic couples in which the difference in potential is high (for instance, zinc and copper [70 mV in seawater]) can generate more current-and therefore, more corrosion-than couples with a lower potential difference, such as naval brass and copper (40 mV in seawater).
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