Ohm’s Law gives the relation between voltage and current. Whenever an electric potential difference (V) is applied across two points of the conductor, the current (I) flows through it. The flow of current is opposed by the resistance (R) of the conductor. The value of resistance (R) will remain constant for all value of voltages and currents. This relation was expressed first of all by a German Scientist, George Simon Ohm that is why it is called Ohm’s Law.

Ohm’s Law states that current flowing between to applied voltage or points of conductor is directly proportional to applied voltage or potential difference between two points of conductor. Provided the temperature and other physical conditions of the conductor do not change.

Mathematically,

In other words, Ohm’s Law can also be defined as,

The ratio of potential difference across any two points of a conductor to the current flowing through the conductor is always constant. This constant is called resistance (R).

The linear relationship (I α V) does not apply to all non-metallic conductors. For example for silicon carbide, the relationship is given by V = kI^{X} where k and x being constants; x is always less than unity.

Limitations of Ohm’s Law

- Ohm’s Law is not applied to non-linear resistors like vacuum radio value, semiconductors etc.
- It is not applied to arc lamps.
- Electrolytes where enomous gases are produced on either electrode.
- It is not applied to unilateral elements.

Applications of Ohm’s Law

Ohm’s Law applies to linear circuits to find resistance, current and voltages.