Question

What is potential difference? Define its SI unit. Which instrument is used to measure it and how it is used?

Answer 1

1. Definition of potential difference - The potential difference between two points in a circuit is the work done in moving unit positive charge (i.e., one coulomb) from one point to the other.
2. Unit of potential difference
   1. It is denoted by the symbol $V.$ It is a scalar quantity.
   2. If $W$ joule of work is done in bringing the test charge $Q$ coulomb from one point $A$ in an electric field to other point $B$ then the electric potential difference $V$ is given as $V=\frac{W}{Q}$
   3. The S.I. unit of work is the joule $J$and that of charge is the coulomb $C$, so the S.I. unit of potential difference is calculated as
      $Unitofpotentialdiffrence=\frac{unitofworkdone\left(J\right)}{unitofcharge\left(C\right)}=\frac{J}{C}orJ{C}^{-1}$
   4. Hence, the S.I unit of potential difference is $\frac{joule}{coulomb}orJ{C}^{-1}$.
3. The potential difference is measured by an instrument called a voltmeter..