Question

Which quantity is denoted by Joule/Coulomb?

Answer 1

Hint:The quantities of which units are joule and coulomb have to be known. Joule is related to work done as well as energy whereas Coulomb is related to the charge. Now, when a unit positive charge is to be brought from an infinite distance to an electric field there must be some work to be done. This work is related to some electrical quantity. This electrical quantity is defined by the ratio of the work done to the charge. Here in the problem, the given ratio is of the unit of work done and the unit of charge. From this concept, the answer can be determined.
Formula used:
The electric potential $V = \dfrac{{W{\text{(Work - done)}}}}{{Q{\text{(charge)}}}}$

Complete step-by-step solution:
The given unit is $\dfrac{{{\text{Joule}}}}{{{\text{Coulomb}}}}$.
Joule is the unit of work done and Coulomb is the unit of the charge.
So, the quantity should be equal to Work done/ charged.
Now, by definition when a unit positive charge is brought from an infinite distance to an electric field some work is done, this work is called the electric potential.
$\therefore $Work done $(W)$= Electric potential ${\text{(V)}}$
So, for $Q$ charge, the work done will be $W = V \times Q$
$ \Rightarrow V = \dfrac{W}{Q}$
So , the equation for the unit will be,
Unit of electric potential = $\dfrac{{{\text{Joule}}}}{{{\text{Coulomb}}}}$
Therefore, the quantity which is denoted by Joule/Coulomb is Electric potential.

 Note:The work done due to the bringing of charge into the electric field is stored as an electric potential energy inside the charge.
$\therefore $ Electric potential energy $(U) = V \times Q$
Therefore, the electric potential can be defined by the stored potential energy inside a point of an electric potential.
In the above relation, the work done and the charge are scalar quantities, so the electrical potential is a scalar quantity. In general, the SI unit of the electric potential is volt.