State and explain Ohm's law.

(N/A) In $1828$, German scientist George Simon Ohm formulated the law as follows:
"Under constant physical conditions, the ratio of the potential difference $(V)$ between two points of a conductor to the current $(I)$ flowing through it is constant."
$\therefore V \propto I$
$\therefore V = RI$, where $R$ is the constant of proportionality.
$\therefore \frac{V}{I} = R$
Here, $R$ is called the resistance of the conductor. The unit of resistance is $\frac{\text{Volt}}{\text{Ampere}} = \text{Ohm} (\Omega)$. The dimensional formula for resistance is $[M^1 L^2 T^{-3} A^{-2}]$.