Volts

Volts (symbol V) are the SI unit of electric potential difference, the potential energy per unit charge between two points in an electric circuit. The unit is named after Alessandro Volta. One volt is defined as one joule of work required to move one coulomb of charge between two points, i.e., 1 V = 1 J/C. In common usage, a volt measures how strongly an electric source or device pushes charges through a circuit.

The volt is a derived unit. In electrical practice, voltage can be produced by sources such as batteries, generators, or power supplies, and is observed across components when current flows. The term electromotive force (EMF) is sometimes used for the energy provided by a source, whereas the actual voltage across a component may differ due to internal resistance.

Voltage is measured with a voltmeter, connected across the element or circuit point of interest. For alternating current (AC) signals, values are often specified as root-mean-square (RMS), whereas direct current (DC) voltages are constant. The relationship to current and resistance is described by Ohm's law: V = I R, and electrical power by P = V I.

Common examples include household mains voltages, which vary by region (about 120 V in some countries and 230 V in others), automotive systems that commonly use 12 V DC, and electronic devices that often operate at 3.3 V or 5 V DC internal rails.

Safety note: high voltages can pose serious hazards; proper insulation and precautions are essential.