Imperial and US customary measurement systems (42 US gallons, 34.97 imperial gallons or 159.0 litres) used in the oil industry has the dimension of volume and could be replaced by the gallon, cubic metre or litre. The definitions of potential difference (volt), electric current (ampere), electrical resistance (ohm) were defined in terms of metric units, international agreement having been reached at a series of IEC Congress in Chicago between 1881 and 1906 when the electrical industry was in its infancy. At that time the metric system had become established in continental Europe while in the United Kingdom metrication was an active issue. Similarly, the units of
Open-circuit voltage potential drop across the resistance C. The resistor B does not affect the open-circuit voltage. Since no current is flowing through it, there is no potential drop across it. So we can easily ignore it. Therefore, the potential drop across the resistance C is "V." This is just an example. Many other ways can be used. Open-circuit voltage Open-circuit voltage (abbreviated as OCV or V ) is the difference of electrical potential between two terminals of a device when disconnected from any circuit. There is no external load connected. No external electric current flows between the terminals. Alternatively, the open-circuit