Kirchhoff Kirchhoff Gustav Robert (1824 ~ 1887), a German physicist. 1824 was born in konigsberg, Prussia (now Kaliningrad, Russia), and 1887 10 died in Berlin. Kirchhoff studied physics at the University of Konigsberg. 1847 After graduation, I went to teach at the University of Berlin. Three years later, he went to Brecey University as an adjunct professor. 1854 was recommended by R.W.E as a professor at the University of Heidelberg. 1875 unable to do experiments due to poor health, he became a professor of theoretical physics at the University of Berlin until his death.

1845, at the age of 2 1, he published his first paper, and put forward two circuit laws to stabilize the relationship between current, voltage and resistance in the circuit network, namely the famous Kirchhoff first circuit law and Kirchhoff second circuit law, which solved the circuit problems in electrical design. Later, the flow and distribution of electricity in the circuit were studied, thus clarifying that the potential difference between two points in the circuit is consistent with the electrostatic potential in dimension and unit. Make Kirchhoff's circuit law have wider significance. Until now, Kirchhoff's circuit law is still an important tool to solve complex circuit problems. Kirchhoff is known as "the master of circuit solving".

During his stay at Heidelberg University, he cooperated with Benson to establish a spectral analysis method. By burning various elements on the bunsen burner, some bright line spectra with specific wavelengths are emitted, from which the existence of such elements can be judged very sensitively. Using this new method, he discovered the elements cesium and rubidium.

1859, Kirchhoff did the experiment of burning salt with lamp flame. In the process of studying this experimental phenomenon, the law of thermal radiation was obtained, which was later called Kirchhoff's law: the ratio of emission ability to absorption ability of any object has nothing to do with the characteristics of the object, but a universal function of wavelength and temperature. Judging from this, the dark line of the solar spectrum is the result of element absorption in the solar atmosphere. This provides an important method for the composition analysis of the sun and stars, and astrophysics has entered a new stage because of the application of spectral analysis methods. In 1862, he further obtained the concept of absolute boldface. His law of thermal radiation and the concept of absolute blackbody are one of the keys to open a new era of physics in the 20th century. 1900 M Planck's quantum theory originated here.

Kirchhoff's contribution to optical theory is to give a stricter mathematical form of huygens-fresnel principle. It has a great influence on the development of theoretical physics in Germany. He is the author of four volumes of lectures on mathematical physics.