Electric potential, potential difference, voltage, OHM’s law
Electric potential
Work done in carrying one coulomb of charge from infinity to any point is called the electric potential of that point. SI unit of potential is voltage denoted by ‘V’.
Potential difference
Work done in carrying one-coulomb charge or unit charge from point ‘A’ to point ‘B’ is called the potential difference between point A and B. It is also measured in Volt, denoted by VAB.
where VAB is the potential difference between point A and B or the Potential of point A with respect to point B. And VA is the potential of point A, VB is the potential at point B.
Instantaneous voltage
If the voltage is changing with respect to time then we have to find instantaneous voltage. Instantaneous voltage is a voltage at a given instant of time.
\[v=\frac { dw }{ dq }\]
What do you mean by one volt of potential or voltage or potential difference?
If work done in carrying one-coulomb charge from point A to point B is one Joule, then the potential difference between point A and B is one Volt.
\[1V=\frac { 1J }{ 1s }\]
How does voltage work? How voltage creates a current in an electric circuit?
When a conducting wire (consisting of several atoms) is connected to a battery (a source of electromotive force), the charges are compelled to move; positive charges move in one direction while negative charges move in the opposite direction. This motion of charges creates an electric current. Here battery produces a potential difference between the conductor which produces an electric field that applies force on electrons. Electrons require some work or energy transfer to flow inside a conductor, this work is performed by electromotive force (emf) typically represented by the battery. This emf is also called potential energy or potential difference.
Polarity of voltage
VAB=VA-VB=-(VB-VA)=-VBA
from the below figure, we can say that the VA is greater than VB by VAB or VB is greater than by VA by VBA . But as we can see from the above equation both statements have the same meaning.
Define OHM’s law
OHM’s law states that the current flowing through a conductor is directly proportional to the voltage across it. Generally, OHM’s law shows the relation between voltage and current. The electrical elements which follow OHM’s law are called linear elements. The relationship between current and voltage is founded by Georg Simon Ohm.
\[V\propto I \\ \Rightarrow \frac { V }{ I } =constant\quad (R) \\ \Rightarrow V=IR\]
Here R is the resistance of that conductor. It depends on conductor to conductor. We will discuss resistance and resistor briefly in our next post.