Voltage in physics is the electric potential difference between two points in a circuit or electric field, and it tells you how much energy each unit of charge can gain or lose when moving between those points.

Quick Scoop: Core Idea

  • Voltage measures how much energy is transferred per unit charge.
  • In symbols:

V=ΔUQV=\frac{\Delta U}{Q}V=QΔU​

where VVV is voltage, ΔU\Delta UΔU is change in electric potential energy (in joules), and QQQ is charge (in coulombs).

  • The SI unit of voltage is the volt (V), where 1 volt = 1 joule per coulomb (1 V = 1 J/C).

A helpful picture: think of voltage like pressure in a water pipe—higher pressure pushes water harder, and higher voltage “pushes” charges harder through a conductor.

How Physicists Define It

  • In a static electric field, voltage is the work done per unit positive charge to move it from one point to another.
  • Formally: it is the difference in electric potential between two points, not something at a single point by itself.
  • Because it is a difference , you always talk about “voltage between A and B”, like 5 V between two terminals.

Another common relation in circuits is Ohm’s law:

V=IRV=IRV=IR

where III is current and RRR is resistance, connecting voltage to how much current flows through a given resistance.

Everyday Interpretation

  • When you see “1.5 V battery” or “230 V mains”, that number tells you how much energy per coulomb the source can give to moving charges.
  • Higher voltage generally means the source can push more energy per unit charge—like higher water pressure can drive more powerful jets.

So, in one line: voltage is the energy per unit charge (potential difference) that drives electric current, measured in volts (J/C).