Kirchhoff's laws

Not to be confused with Kerckhoffs's principle.

There are several Kirchhoff's laws, all named after Gustav Kirchhoff:

 Kirchhoff's circuit laws (electrical circuits)
 Kirchhoff's law of thermal radiation
 Kirchhoff equations (fluid dynamics)
 Kirchhoff's three laws of spectroscopy
 Kirchhoff's law of thermochemistry