Kirchhoff, Gustav Robert (1824-1887), a German physicist. Investigations in spectrum analysis enabled Kirchhoff and Robert Wilhelm Bunsen to discover the elements cesium (1860) and rubidium (1861). Kirchhoff formulated laws concerning heat radiation and electrical circuits. He was born in the East Prussian city of Königsberg (now Kaliningrad, Russia) and studied at the university there. Kirchhoff taught physics at the universities of Breslau, Heidelberg, and Berlin.