An induced electromotive force (emf) always gives rise to a current whose magnetic field opposes the original change in magnetic flux.
Lenz's law is shown with the minus sign in Faraday's law of induction, which indicates that the induced emf () and the change in flux () have opposite signs.
For a rigorous mathematical treatment, see electromagnetic induction and Maxwell's equations.
When net positive work is applied to a charge , it gains momentum. The net work on thereby generates a magnetic field whose strength (in units of magnetic flux density (1 Tesla = 1 volt-second per square meter)) is proportional to the speed increase of . This magnetic field can interact with a neighboring charge , passing on this momentum to it, and in return, loses momentum.
can also act on in a similar manner, by which it returns some of the emf that it received from . This back-and-forth component of emf contributes to magnetic inductance. The closer that and are, the greater the effect. When is inside a conductive medium such as a thick slab made of copper or aluminum, it more readily reacts to the emf sent to it by . The energy of is not "instantly" consumed only as heat generated by the current of but is also stored in ''two'' opposing magnetic fields. The energy density of magnetic fields tends to vary by the square of the magnetic field's intensity; however, in the case of magnetically non-linear materials such as ferromagnets and superconductors, this relationship breaks down.
:
In general the incremental amount of work per unit volume ''δW'' needed to cause a small change of magnetic field ''δ''B is:
:
Category:Levitation Category:Electrodynamics
ar:قانون لنتس ast:Llei de Lenz bn:লেন্জের সূত্র ca:Llei de Lenz cs:Lenzův zákon da:Lenz' lov de:Lenzsche Regel et:Lenzi reegel el:Κανόνας του Λεντς es:Ley de Lenz eo:Leĝo de Lenz fa:قانون لنز xal:Ленцин зокал ko:렌츠의 법칙 hi:लेंज का नियम it:Legge di Lenz he:חוק לנץ hu:Lenz-törvény mk:Ленцов закон nl:Wet van Lenz ja:レンツの法則 no:Lenz' lov pl:Prawo Lenza pt:Lei de Lenz ru:Правило Ленца simple:Lenz's law sk:Lenzov zákon sl:Lenzovo pravilo sr:Ленцов закон fi:Lenzin laki sv:Lenz lag ta:லென்சின் விதி tr:Lenz yasası uk:Правило Ленца vi:Định luật Lenz zh:楞次定律This text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.
Name | Maurice Lenz |
---|---|
Birth date | March 23, 1890 |
Birth place | Kovno, Russia |
Death date | January 4, 1974 |
Resting place coordinates | |
Nationality | Russian-American |
Education | Medical doctor, 1913 |
Alma mater | Columbia University College of Physicians and Surgeons |
Employer | Columbia University College of Physicians and Surgeons |
Occupation | Professor, Radiation Oncology |
Years active | 1913-1974 |
Title | Director, Division of Cancer of the City of New York |
Religion | Jewish |
Spouse | Anna Marie Malmberg |
Footnotes | }} |
Maurice Lenz (March 23, 1890 – January 4, 1974) was a pioneer in the field of radiation therapy. Born in Kovno, Russia (now Kaunas, Lithuania), Lenz studied at New York University and Bellevue Medical College, and received his medical degree from Columbia University College of Physicians and Surgeons in 1913. He was a professor of radiation oncology at the Columbia University College of Physicians and Surgeons, a past president of the American Radium Society and held many other clinical and administrative roles throughout a long career in medicine.
According to the Columbia University Health Sciences Library archivist Stephen C. Novak:
Lenz's unusual linguistic abilities - besides Russian and English he was fluent in French, German, Portuguese, and Spanish - made him an internationally known figure among radiotherapists. He led the US delegation to the Second Inter-American Congress of Radiology in 1946 and was a member of the Third Congress in 1949. At the request of the US State Dept., he undertook lecture tours in the USSR in 1959 and 1967. In 1971, he represented the US at the 50th anniversary celebration of the Radium Institute of the Curie Foundation.
Lenz served in the U.S. Army Medical Corps, as a lieutenant in general medical practice, during World War I. Following the war, he studied in Europe at Freiburg University in Germany and completed a fellowship in radiation therapy at the Curie Institute in Paris, France where he established personal friendships with famous researchers in radiation, including Claudius Regaud, Octave Monod, François Baclesse and Antoine Lacassagne. Returning to the United States in 1925, Lenz served as director of radiotherapy at the Montefiore Hospital in New York City until 1930. He held the same position at the Presbyterian Hospital of Columbia University and the Frances Delafield Hospital and was the director of the Division of Cancer of the City of New York (concurrently) through 1955. As a visiting professor of the World Health Organization in 1959, Lenz visited countries throughout Asia and the Soviet Union. Despite his retirement from the practice of medicine, Dr. Lenz continued his studies with research fellowships, at the Curie Institute and in ovarian cancer with the Radiumhemmet in Stockholm, Sweden.
Category:Cancer researchers Category:Columbia University faculty Category:Jewish scientists Category:People from Kaunas Category:Radiologists Category:United States Army Medical Corps officers Category:1890 births Category:1974 deaths
This text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.
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