0volt

0volt (0 volt) is the electrical potential difference that equals zero volts. In circuit theory, the potential of any point is defined relative to a reference, or ground; when the point’s potential matches the reference, the voltage difference is 0 V. The concept is central to defining voltages within a circuit and to establishing a common return path for current.

Ground is commonly treated as the 0 V reference, but in practice earth and circuit grounds may have a small impedance to true zero. Designers select a 0 V rail as a stable reference to simplify calculations and measurements. A node measured at 0 V relative to ground is said to be at equal potential with the reference point.

In digital electronics, 0 V frequently corresponds to a logic low, while higher voltages indicate a logic high, though exact thresholds vary by technology (for example TTL or CMOS). In alternating-current systems, instantaneous voltage passes through 0 V many times per cycle, even though the RMS or peak values are nonzero; zero-crossings are used in synchronization tasks.

Measurement of 0 V requires a careful reference and proper instrumentation; stray voltages, grounding issues, or floating nodes can make measurements appear nonzero. Proper grounding and shielding reduce such effects.

See also: voltage, ground, reference potential, electrical potential.