Voltage is used for source unit in an electrical circuit. There are two types of voltage source used in electrical circuit theory: DC voltage source and AC voltage source. In practical application and also in various mathematical problems, we need to express voltage in short form. There are some definite rules to express units or symbols for representing engineering physical terms. Suppose when we want to measure our weight then we get it is expressed in kg (kilogram) because Kg is the unit of weight. Similarly unit of DC (same in AC) voltage is volt and it is expressed as V. Here, some dc voltage symbols are mentioned below:

Schematic symbol for DC voltage

DC voltage single battery or cell                                       –           +



DC voltage symbol for multiple battery                  –           +             –         +



Dc voltage source symbol                                    –                   +                                             –        +




Voltmeter (instrument) symbol



DC power symbol

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Voltage unit: V for volts / mV for milivolts / KV for kilovolts / MV for megavolts


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