Voltage (V)

Voltage, or electric potential difference, describes the amount of electric potential energy per unit charge between two points in an electric field. It is measured in volts (V), the SI unit of voltage.

One volt corresponds to the potential difference required to drive a current of 1 ampere through a resistance of 1 ohm, dissipating 1 watt of power.

Mathematical Definition

Voltage is defined as energy per unit charge:

V = W / Q

where:

• V = voltage (volts)

• W = energy (joules)

• Q = electric charge (coulombs)

According to Ohm’s Law, voltage is also related to current and resistance:

V = I × R

where:

• I = current (amperes)

• R = resistance (ohms)

Practical Applications

• AA battery: Provides 1.5 V

• Power outlets: Deliver 120 V (North America) or 230 V (Europe)

• USB: Standard connection provides 5 V

• Industrial equipment: Often operates at 400 V three-phase

• Electric vehicles: Use battery voltages from 200 V to over 800 V

Voltage is a foundational quantity in electrical engineering, relevant from microelectronics (millivolt range) to power transmission (kilovolt range).