Gustav Kirchhoff

Gustav Robert Kirchhoff (12 March 1824 – 17 October 1887) was a German physicist who contributed to the fundamental understanding of electrical circuits, spectroscopy, and radiation by heated objects. He coined the term black body radiation in 1862. 
He proposed two sets of independent concepts in both circuit theory and thermal emission. They are all called 'Kirchhoff's laws' after him, as well as a law of thermochemistry. The Bunsen–Kirchhoff Award for spectroscopy is named after him and his colleague, Robert Bunsen. He also discovered rubidium with Bunsen in 1861.