Question

State Ohm's law. How it is used to define the resistance?

Answer 1

Ohm's law states that “ At constant temperature, the current flowing through the conductor is directly proportional to the potential difference applied across the conductor”. If $\mathrm{I}$ be the current flows through the conductor and potential difference be $\mathrm{V}$ applied across the conductor,

$\mathrm{I}\propto \mathrm{V}$

$\mathrm{I}=\frac{\mathrm{V}}{\mathrm{R}}$

where, R is a constant called resistance of the conductor. Ohm $\left(\mathrm{\Omega }\right)$ is the unit of resistance.

If current of $1\mathrm{A}$ is flowing through a conductor, when a potential difference of $1\mathrm{V}$ is applied across it, then resistance

$$\begin{gathered} \mathrm{R}=\frac{1\mathrm{V}}{1\mathrm{A}} \\ \mathrm{R}=1\mathrm{\Omega } \end{gathered}$$

Therefore, 1 ohm is the resistance of the conductor, when a potential difference of $1\mathrm{V}$ is applied across the conductor and the current of $1\mathrm{A}$ flows through it.