# Ohm’s Law

## Ohm’s Law

Definition : According to the Ohm’s law at constant temperature, the current flowing through a conductor is directly proportional to the potential difference across the conductor.

Thus, if  I is the current flowing through a conductor and V is the potential difference (or voltage) across the conductor, then according to Ohm’s law.

I ∞ V         (when T is constant)

where R is a constant called the resistance of the conductor.

Equation (i) may be written as,

V = I × R  ……(ii)

## Unit of resistance

The SI unit of resistance (R) is ohm. Ohm is denoted by the Greek letter omega (Ω).

From Ohm’s law,

Now, if,            V = 1 volt and I = 1 ampere

Thus, 1 ohm is defined as the resistance of a conductor which allows a current of 1 ampere to flow through it when a potential difference of 1 volt is maintained across it.

## Results of Ohm’s law

• Current flowing through a conductor is directly proportional to the potential difference across the conductor.
•  When the potential difference in a circuit is kept constant, the current in inversely proportional to the resistance of the conductor.   I 1/R
• The ratio of potential difference to the current is constant. The value of the constant is equal to the resistance of the conductor (or resistor). V/I = R