Editing Voltage (section)

== Applications ==
[[File:US Navy 110315-N-0278E-002 High-voltage electricians from Naval Facilities Engineering Command (NAVFAC) Hawaii reconfigure electrical circuitry and.jpg|thumb|upright|Working on [[high voltage|high-voltage]] power lines]]

Specifying a voltage measurement requires explicit or implicit specification of the points across which the voltage is measured.  When using a voltmeter to measure voltage, one electrical lead of the voltmeter must be connected to the first point, one to the second point.

A common use of the term "voltage" is in describing the voltage dropped across an electrical device (such as a resistor). The [[voltage drop]] across the device can be understood as the difference between measurements at each terminal of the device with respect to a common reference point (or [[ground (electricity)|ground]]). The voltage drop is the difference between the two readings. Two points in an electric circuit that are connected by an ideal conductor without resistance and not within a changing [[magnetic field]] have a voltage of zero. Any two points with the same potential may be connected by a conductor and no current will flow between them.

===Addition of voltages===
The voltage between ''A'' and ''C'' is the sum of the voltage between ''A'' and ''B'' and the voltage between ''B'' and ''C''. The various voltages in a circuit can be computed using [[Kirchhoff's circuit laws]].

When talking about [[alternating current]] (AC) there is a difference between instantaneous voltage and average voltage. Instantaneous voltages can be added for [[direct current]] (DC) and AC, but average voltages can be meaningfully added only when they apply to signals that all have the same frequency and phase.