Gustav Robert Kirchhoff (1824–1887), a German physicist noted for his formulation of laws related to the conduction of electricity. In Laws of Closed Electric Circuits, published in 1845, he stated what are now known as Kirchoff's Current and Voltage Laws. The first law states that the sum of the currents into a given node equals the sum of the currents out of that node. The second law states that the sum of electromotive forces in a loop in the network equals the sum of potential drops, or voltages across each of the resistances, in the loop. Kirchoff also made major contributions to the study of spectroscopy, and advanced research into blackbody radiation. With Robert Bunsen, he invented the spectroscope (1859), a prism-based device that separated light into its primary chromatic components, i.e., its spectrum. With the spectroscope they began studying the spectral "signature" of various chemical elements in gaseous form. Kirchoff and Bunsen discovered two alkali metals (1860), cesium and rubidium, with the aid of the spectroscope. Most previous elements had been discovered either as the products of chemical reactions or through their release by electrolysis. This discovery inaugurated a new era in the methods used to find new elements. In the early 1860s, Kirchhoff produced the first detailed map of the solar spectrum.
- Chemical Achievers: Robert Wilhelm Eberbard Bunsen and Gustav Robert Kirchhoff, Chemical Heritage Foundation.
- Kirchhoff Biography, University of St. Andrews, Scotland, School of Mathematics and Statistics.
- American Chemical Society
- Society of Chemical Industry
- The Chemists' Club