7. Ohm's law

Georg Simon Ohm, a German physicist, conducted various experiments and formulated Ohm's law. The law describes the relationship between potential difference and current.

 

Ohm's law states that,

Mathematically, it is written as

 

 

Hence,

 

 

(or)

 

The value of the proportionality constant found in the above equation is $\frac{1}{R}$.

 

Therefore,

 

 

Where $V$ is the potential difference, $I$ is the current flowing through a conductor, and $R$ is the resistance of a material. The resistance is constant for a material (e.g., copper) at a given temperature.

 

The above equation can also be written as,

 

 

In terms of units, the resistance $R$ of a conductor is said to be $1\ ohm$ with a potential difference of $1\ volt$, causing the current of $1\ ampere$ to flow through the conductor. Then,

 

 

Graphical representation:
The graph between the potential difference ($V$) and the current ($I$) is a straight line for a conductor since $V$ is proportional to $I$.