What is EMF, potential difference and voltage?
In this article, we describe what is EMF, its potential difference and voltage, what is the difference. In materials on electrical engineering and electronics, you can often find three physical quantities that have the same unit of measurement – Volt: the difference in electrical potentials, electrical voltage and EMF – electromotive force.
To get rid of the confusion in terms once and for all, let’s figure out what are the differences between these three concepts. To do this, consider in detail each of them separately. To learn in more detail about What is EMF, please keep reading until we are done.
Electrical potential difference
Today physicists know that electric charges or changing magnetic fields are sources of electric fields. When we consider certain points A and B in an electrostatic field of a known intensity E, we can immediately talk about the difference in electrostatic potentials between these two points at the current time.
This potential difference is found as the integral of the electrical strength between points A and B, located in a given electric field at a certain distance from each other:
In practice, such a characteristic as a potential refers to one electric charge, which theoretically can be motionlessly installed at a given point of the electrostatic field, and then the value of the electric potential for this charge q will be equal to the ratio of the potential energy W (the interaction of a given charge with a given field) to the value of this charge:
From this it follows that the potential difference turns out to be numerically equal to the ratio of work A (work in fact is a change in the potential energy of a charge) performed by a given electrostatic field when the considered charge q is transferred from field point 1 to field point 2 to the value of this test charge q:
This is the practical meaning of the term “potential difference” in relation to electrical engineering, electronics, and in general – to electrical phenomena.
And if we are talking about some kind of electrical circuit, then we can also judge about the potential difference between two points of such a circuit, if an electrostatic field is acting in it at a given moment , and precisely because the points of the circuit under consideration will be simultaneously in an electrostatic field a certain tension.
As mentioned above, the electrical potential difference is measured in volts (1 volt = 1 J / 1C).
Electric voltage U
Now consider such a concept as an electric voltage U between points A and B in an electric field or in an electric circuit. Electric voltage is a scalar physical quantity that is numerically equal to the work of an effective electric field (including external fields!) Performed when a unit electric charge is transferred from point A to point B.
Electrical voltage is measured in volts, just like the electrical potential difference. If you want to read about The Asterisk War Season 3, please read this. In the case of voltage, it is generally accepted that charge transfer will not change the distribution of charges that are sources of an effective electrostatic field. And the voltage in this case will consist of the work of electrical forces and the work of outside forces.
