Difference Between Electric Potential and Electric Potential Energy

Electric Potential vs Electric Potential Energy

Electric potential and electric potential energy are two very valuable concepts in electric fields and electromagnetic theory. In this article, we will discuss the basics of electric potential and electric potential energy first and then the difference between the two.

What is Electric Potential?

When discussing the electric potential, a clear understanding of electric field is required to interpret the term. All electric charges, whether they are moving or stationary, produce an electric field. An electric field can also be produced using any time varying magnetic fields. There are several key factors of electric fields, which are pertinent to know. These are electric field intensity, electric field potential and electric flux density. The electric field intensity is defined as the force on a unit point charge from the electric field. This is given by the formula E = Q/4πεr²; where Q is the charge, ε is the electric permittivity of the medium, and r is the distance of the point from the point Q charge. The force on a point charge q placed at that point is equal to F = Qq/4πεr2. Since q is 1 coulomb, this is also equal to the electric field intensity. The electric potential of a point is defined as the energy required to bring a point charge of 1 coulomb from infinity to the point the potential is measured. This energy is equal to the work done on the charge when bringing the charge from infinity to the point. If both the charges are positive, the force that has to be applied to take the test charge from infinity to the point is always equal and antiparallel to the repulsion force between the two charges. By integrating F, from infinity to r, with respect to dr, we get the electric potential (V) of the point, which is Q/4πεr. Since r is always positive, if the charge is negative, the electric potential is also negative. The units of electric potential are joule per coulomb. A static electric field is a conservative field. Therefore, the electric potential of a static electric field is path independent. The electric potential of such field depends only on the position.

What is Electric Potential Energy?

Electric potential energy is defined as the energy stored due to electric potential when taking a charge from infinity to the given point. It can be seen that, since the electric potential is equal to the work required to bring a unit charge, the electric potential energy is the product of the electric potential and the charge that is brought. Since potential energy = V * q, if both V and q are of the same sign, which means that the Q and q are of the same sign, the potential energy is positive. An external work is required to bring the charge. If signs are different, the potential energy becomes negative. This indicates the work is done from the system itself.