electric voltage

Voltage is electric potential energy per unit charge, measured in joules per coulomb             ( = volts). It is often referred to as "electric potential", which then must be distinguished from electric potential energy by noting that the "potential" is a "per-unit-charge" quantity. Like mechanical potential energy, the zero of potential can be chosen at any point, so the difference in voltage is the quantity which is physically meaningful. The difference in voltage measured when moving from point A to point B is equal to the work which would have to be done, per unit charge, against the electric field to move the charge from A to B

V = φ₂ - φ₁

V is the voltage between point 2 and 1 in volts (V

φ₂ is the electric potential at point #2 in volts (V

φ₁ is the electric potential at point #1 in volts (V 

In an electrical circuit, the electrical voltage V in volts (V) is equal to the energy consumption E in joules (J)

divided by the electric charge Q in coulombs (C)

V is the voltage measured in volts (V)

E is the energy measured in joules (J)

Q is the electric charge measured in coulombs (C)

Voltage in series

The total voltage of several voltage sources or voltage drops in series is their sum

V_T = V₁ + V₂ + V₃

V_T - the equivalent voltage source or voltage drop in volts (V

V₁ - voltage source or voltage drop in volts (V

V₂ - voltage source or voltage drop in volts (V

V₃ - voltage source or voltage drop in volts (V

Voltage in parallel

Voltage sources or voltage drops in parallel have equal voltage

V_T = V₁ = V₂ = V₃ 

V_T - the equivalent voltage source or voltage drop in volts (V)

V₁ - voltage source or voltage drop in volts (V)

V₂ - voltage source or voltage drop in volts (V)

V₃ - voltage source or voltage drop in volts (V)

Voltage calculation with Ohm's law

V_R = I_R × R

V_R - voltage drop on the resistor measured in volts (V)

I_R - current flow through the resistor measured in amperes (A)

R - resistance of the resistor measured in ohms (Ω)