Field extensionIn mathematics, particularly in algebra, a field extension is a pair of fields such that the operations of K are those of L restricted to K. In this case, L is an extension field of K and K is a subfield of L. For example, under the usual notions of addition and multiplication, the complex numbers are an extension field of the real numbers; the real numbers are a subfield of the complex numbers. Field extensions are fundamental in algebraic number theory, and in the study of polynomial roots through Galois theory, and are widely used in algebraic geometry.
Electromagnetic fieldAn electromagnetic field (also EM field or EMF) is a classical (i.e. non-quantum) field produced by moving electric charges. It is the field described by classical electrodynamics (a classical field theory) and is the classical counterpart to the quantized electromagnetic field tensor in quantum electrodynamics (a quantum field theory). The electromagnetic field propagates at the speed of light (in fact, this field can be identified as light) and interacts with charges and currents.
French colonial empireThe French Colonial Empire (Empire colonial français) comprised the overseas colonies, protectorates and mandate territories that came under French rule from the 16th century onward. A distinction is generally made between the "First French colonial empire," that existed until 1814, by which time most of it had been lost or sold, and the "Second French colonial empire," which began with the conquest of Algiers in 1830. At its apex between the two world wars, the second French colonial empire was the second-largest colonial empire in the world behind the British Empire.
French GuianaFrench Guiana (ɡiˈɑːnə or ɡiˈænə; Guyane ɡɥijan; Lagwiyann la.ɡɥi.jãn) is an overseas department of France located on the northern coast of South America in the Guianas. Bordered by Suriname to the west and Brazil to the east and south, French Guiana covers a land area of , and is inhabited by 301,099 people. French Guiana is the second-largest region of France (more than one-seventh the size of Metropolitan France) and the largest outermost region within the European Union. It has a very low population density, with only .
