Electrical Potential Difference and Definition of Voltage

 

We can use electric field vector to characterize static electric field in a space. By observing the movement of charge particles inside an electric field, one can predict the exact characteristics of that field. If the field is strong enough, the deflection of charged particle in parabolic path will be more sharp and if the field is weak, deflection is less. But it is not the practical way of measuring the intensity of an electric field. Another physical quantity is there which is much easier to measure and also used to characterize an electric field and this quantity is known as electric potential difference.

 

Electrical potential V(t) of a position in the electrical field is such that, electric potential energy is required to place a particle of charge q at that position, would be the product of charge of the particle q and the potential of that position V(t). That is potential energy U(t) = q.V(t). The SI unit of electrical potential is Volt after name of Italian physicist Alessandro Volta (1745 - 1827).

Voltmeter is used to measure the potential difference between two points.

There is a misconception about potential and voltage. Many of us think that both are the same. But voltage is not exactly potential, it is the measure of electric potential difference of two points.

 

Electrical Potential and Electrical Field Vector

Electrical potential and electrical field vector, both characterize the same thing that is space of electrical field. Since both electric potential and electrical field vector describe an electric field, they are related.

 

dV = - E.ds where dV is the potential difference between two points separated by a distance ds and electrical field vector is E.

 

Definition of Potential Difference or Voltage

After going through the above portion of voltage theory we can now establish a definition of potential difference, definition of voltage in few words. Which says

Voltage is the difference in electric potential energy per unit charge between two points. Voltage is the work to be done, upon an unit charge to move between two points, against a static electric field. A voltage which is a measure of electric potential difference, is the cause of electrical current to flow in a closed circuit.