8. Ohm's law

In \(1827\), Georg Simon Ohm, a German physicist, conducted various experiments and formulated Ohm's law. The law describes the relationship between potential difference and the current flowing in a metallic wire.

 

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,

 

 

The current flowing through a resistor is inversely proportional to its resistance.

 

 

When the resistance is doubled, then the current is cut in half. Sometimes, in practical applications, the current needs to be increased or decreased in an electric circuit. In such cases, a rheostat is used to change the resistance in the circuit.