Browse Definitions :


The volt (symbolized V) is the Standard International (SI) unit of electric potential or electromotive force. A potential of one volt appears across a resistance of one ohm when a current of one ampere flows through that resistance. Reduced to SI base units, 1 V = 1 kg times m2 times s-3 times A-1 (kilogram meter squared per second cubed per ampere).

voltage can be expressed as an average value over a given time interval, as an instantaneous value at a specific moment in time, or as an effective or root-mean-square (rms) value. Average and instantaneous voltages are assigned a polarity either negative (-) or positive (+) with respect to a zero, or ground, reference potential. The rms voltage is a dimensionless quantity, always represented by a non-negative real number.

For a steady source of direct-current (DC) electric potential, such as that from a zinc-carbon or alkaline electrochemical cell, the average and instantaneous voltages are both approximately +1.5 V if the negative terminal is considered the common ground; the rms voltage is 1.5 V. For standard utility alternating current (AC), the average voltage is zero (the polarity constantly reverses); the instantaneous voltage ranges between approximately -165 V and +165 V; the rms voltage is nominally 117 V.

Voltages are sometimes expressed in units representing power-of-10 multiples or fractions of one volt. A kilovolt (symbolized kV) is equal to one thousand volts (1 kV = 103 V). A megavolt (symbolized MV) is equal to one million volts (1 MV = 106 V). A millivolt (symbolized mV) is equal to one-thousandth of a volt (1 mV = 10-3 V). A microvolt (symbolized µV) is equal to one-millionth of a volt (1 µV = 10-6 V).

Also see Ohm's Law, prefix multipliers, Standard International (SI) system of units, and voltage.

This was last updated in September 2005

Join the conversation

1 comment

Send me notifications when other members comment.

Please create a username to comment.

It is a nice definition but I would like a smaller version so I can read it quickly.


  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

  • PCI DSS (Payment Card Industry Data Security Standard)

    The Payment Card Industry Data Security Standard (PCI DSS) is a widely accepted set of policies and procedures intended to ...

  • risk management

    Risk management is the process of identifying, assessing and controlling threats to an organization's capital and earnings.




  • call tree

    A call tree is a layered hierarchical communication model that is used to notify specific individuals of an event and coordinate ...

  • Disaster Recovery as a Service (DRaaS)

    Disaster recovery as a service (DRaaS) is the replication and hosting of physical or virtual servers by a third party to provide ...

  • cloud disaster recovery (cloud DR)

    Cloud disaster recovery (cloud DR) is a combination of strategies and services intended to back up data, applications and other ...