1845 – Germany

‘First law (Junction law): At any junction point in an electrical circuit, the sum of all currents entering the junction must equal the sum of all currents leaving the junction’

‘Second law (Loop law): For any closed loop in an electrical circuit, the sum of the voltages must add up to zero’

In equation form the first law is **I = I _{1} + I_{2} + I_{3} + I_{4} +…** where

**I**is the total current and

**I**,

_{1}**I**,

_{2}**I**etc. are the separate currents.

_{3}Second law is **V = V _{1} + V_{2} + V_{3} + …** where

**V**is the total voltage and

**V**,

_{1}**V**,

_{2}**V**etc. are the separate voltages.

_{3}These laws are an extension of OHM‘s law and are used for calculating current and voltage in a network of circuits. Kirchhoff formulated these laws when he was a student at the University of Konisburg.

Kirchhoff also showed that objects that are good emitters of heat are also good absorbers. This is Kirchhoff’s law of radiation.