Christian Christiansen (9 October 1843 in Lønborg,

Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of Denmark , establishe ...

– 28 November 1917

Frederiksberg Frederiksberg () is a part of the Capital Region of Denmark. It is formally an independent municipality, Frederiksberg Municipality, separate from Copenhagen Municipality, but both are a part of the City of Copenhagen. It occupies an area of ...

) was a Danish physicist. Christiansen first taught at the local polytechnical school. In 1886, he was appointed to a chair for physics at the

University of Copenhagen The University of Copenhagen ( da, Københavns Universitet, KU) is a prestigious public university, public research university in Copenhagen, Copenhagen, Denmark. Founded in 1479, the University of Copenhagen is the second-oldest university in ...

. He mainly studied

radiant heat Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) is ...

and

optical dispersion In optics, and by analogy other branches of physics dealing with wave propagation, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency; sometimes the term chromatic dispersion is used for specificity to o ...

, discovering the Christiansen effect (Christiansen filter). Around 1917, he discovered the

anomalous dispersion In optics, and by analogy other branches of physics dealing with wave propagation, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency; sometimes the term chromatic dispersion is used for specificity to o ...

of numerous dyes, including aniline red (fuchsine), by recording absorption spectra. In 1884, he confirmed the

Stefan–Boltzmann law The Stefan–Boltzmann law describes the power radiated from a black body in terms of its temperature. Specifically, the Stefan–Boltzmann law states that the total energy radiated per unit surface area of a black body across all wavelengths ...

. Christiansen was elected a member of the Royal Swedish Academy of Sciences in 1902. He was doctoral advisor to

Niels Bohr Niels Henrik David Bohr (; 7 October 1885 – 18 November 1962) was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922 ...

. In 1912, he retired and

Martin Knudsen Martin Hans Christian Knudsen (February 15, 1871 in Hasmark on Funen – May 27, 1949 in Copenhagen) was a Danish physicist who taught and conducted research at the Technical University of Denmark. He is primarily known for his study of molec ...

became professor.

Citations

* C. Christiansen, ''Lærebog i fysik'', Copenhagen, 1892 * C. Christiansen, ''Indledning til den mathematiske Fysik'', 2 Bde, 1887-1889 * C. Christiansen, ''Untersuchungen über die optischen Eigenschaften von fein vertheilten Körpern - Erste Mittheilung''
Ann. Phys., Vol. 23
pp. 298–306, 1884 * C. Christiansen, ''Untersuchungen über die optischen Eigenschaften von fein vertheilten Körpern - Zweite Mittheilung''
Ann. Phys., vol. 24
pp. 439–446, 1885 * C. Christiansen
Elements of Theoretical Physics
' translated into English by W. F. Magie from the German translation of Johannes Julius Christoph Müller (London, McMillan, 1897)

References

External links

* Physics Tree
Christian Christiansen Details

Christiansen effect
Danish physicists Optical physicists 1843 births 1917 deaths Members of the Royal Swedish Academy of Sciences Members of the Royal Society of Sciences in Uppsala {{Denmark-scientist-stub