Ohm's law deals with the relationship between voltage and current in an ideal conductor. This relationship states that:

The potential difference (voltage) across an ideal conductor is proportional to the current through it.

The constant of proportionality is called the resistance, R, which has already been described in the previous section. Ohm's law is given as follows:

V = I R

Here, I is the current through the conductor in units of amperes, V is the potential difference measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms.

Kirchhoff's law is the starting point for analysis of any circuit. In 1845, Gustav Kirchhoff, a German physicist, first described two laws that became central to electrical engineering. The laws were generalized from the work of Georg Ohm. These two laws are: