Voltage is the pressure emitted from an electrical power source. it is a quantitative expression of the potential difference in charge between two points in an electric field. 

Voltage is also known as electromotive force, electric potential difference, electric pressure or electric tension.

In many materials the voltage can be defined using Ohm's Law:

  • Ohm's Law: V= IR
  • V = Voltage 
  • I = Current 
  • R = Resistance 

Ohms law states that the potential difference across the ends of a conductor is proportional to the current flowing through the conductor.