# What is the difference between electric potential, potential difference, and voltage?

I see both terms being used from time to time. Are they interchangeable?

• Yes, They are the same thing. Electric potential is a value if multiplied by a charge value you will get a value of a Potential Energy for that specific particle, That is $PE = Vq$, Where $V$ is the potential, $q$ is the value of a charge in Coulombs and $PE$ is the potential energy in Joules. In other words electric potential's units are Energy per Unit charge that is ($\frac{Joules}{Coulomb}$) and this unit is called Voltage. Dec 25, 2016 at 18:36
• Possible duplicates: physics.stackexchange.com/q/141638/2451 and links therein. Mar 27, 2019 at 12:51

Electrical potential is the energy per unit charge gained or lost when a charge is moved from some reference point at which the potential is defined to be zero.

Voltage is the difference in potential between two arbitrary points at which the potential is not necessarily zero.

For example, the potential at point A relative to a defined reference point (sometimes an infinite distance away) might be 10000 volts, and the potential at point B might be 10100 volts. Then the voltage between B and A is 100 volts.

While they represent the same type of quantity, they have slightly different connotations.

In my experience, "voltage" is not a formal term, and therefore never gets a formal definition. However, it is essentially used in practice to mean "what we measure with a voltmeter." This is an operational definition.

If you use a voltmeter in a static field or a DC circuit, then there is a well-defined potential, and the voltmeter measures the difference in potential.

An oscilloscope is also a kind of voltmeter. Let's say you use an oscilloscope to measure the EMF induced in a coil by a changing magnetic field. Then the thing we're measuring does have units of volts, and can probably be called a voltage, but it is not a difference in potential. There is no well-defined electric potential in this case.

Being a little pedantic, the electric potential is an absolute number, after choosing your gauge, of course.

On the other hand, "voltage" is actually a DIFFERENCE of two potentials. The difference of the potential at one point and another. But we usually set "0 volts" the reference, so they are used interchangably.

• Being a little pedantic, if you have chosen a zero for your potential somewhere (is that what you meant by "gauge"?), then you are measuring differences. Nov 14, 2018 at 2:05