Alfred-Marie Liénard (2 April 1869 in

Amiens Amiens (English: or ; ; , or ) is a city and Communes of France, commune in northern France, located north of Paris and south-west of Lille. It is the capital of the Somme (department), Somme Departments of France, department in the region ...

– 29 April 1958 in

Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...

), was a French

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...

and

engineer Engineers, as practitioners of engineering, are professionals who Invention, invent, design, build, maintain and test machines, complex systems, structures, gadgets and materials. They aim to fulfill functional objectives and requirements while ...

. He is best known for his derivation of the Liénard–Wiechert potentials. From 1887 to 1889 Liénard was a student at the

École Polytechnique (, ; also known as Polytechnique or l'X ) is a ''grande école'' located in Palaiseau, France. It specializes in science and engineering and is a founding member of the Polytechnic Institute of Paris. The school was founded in 1794 by mat ...

and from 1889 to 1892 at the

École des mines de Paris École or Ecole may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * Éco ...

. From 1892 to 1895 he was a

mining engineer Mining engineering is the extraction of minerals from the ground. It is associated with many other disciplines, such as mineral processing, exploration, excavation, geology, metallurgy, geotechnical engineering and surveying. A mining engineer m ...

Valencia Valencia ( , ), formally València (), is the capital of the Province of Valencia, province and Autonomous communities of Spain, autonomous community of Valencian Community, the same name in Spain. It is located on the banks of the Turia (r ...

Marseille Marseille (; ; see #Name, below) is a city in southern France, the Prefectures in France, prefecture of the Departments of France, department of Bouches-du-Rhône and of the Provence-Alpes-Côte d'Azur Regions of France, region. Situated in the ...

, and

Angers Angers (, , ;) is a city in western France, about southwest of Paris. It is the Prefectures of France, prefecture of the Maine-et-Loire department and was the capital of the province of Duchy of Anjou, Anjou until the French Revolution. The i ...

. From 1895 to 1908 he was professor at the École des Mines de Saint-Étienne and from 1908 to 1911 he was professor of electrical engineering at the École des Mines de Paris. In

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

he served in the

French Army The French Army, officially known as the Land Army (, , ), is the principal Army, land warfare force of France, and the largest component of the French Armed Forces; it is responsible to the Government of France, alongside the French Navy, Fren ...

. Liénard worked in the fields of

electricity Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

magnetism Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, ...

, and

mechanics Mechanics () is the area of physics concerned with the relationships between force, matter, and motion among Physical object, physical objects. Forces applied to objects may result in Displacement (vector), displacements, which are changes of ...

. In 1898 (and two years after him

Emil Wiechert Emil Johann Wiechert (26 December 1861 – 19 March 1928) was a German physicist and geophysicist who made many contributions to both fields, including presenting the first verifiable model of a layered structure of the Earth and being among the ...

), he derived what is now called the Liénard–Wiechert potentials. He also investigated problems related to the elasticity and strength of materials, and wrote papers on

thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed b ...

and

hydrodynamics In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in ...

. Along with M. H. Chipart, Liénard developed the

Liénard–Chipart criterion In control theory, the Liénard–Chipart criterion is a stability criterion modified from the Routh–Hurwitz stability criterion, proposed in 1914 by French physicists A. Liénard and M. H. Chipart. This criterion has a computational advantage ...

for determining the stability of a continuous-time system of equations. Liénard was a commander of the

Légion d'honneur The National Order of the Legion of Honour ( ), formerly the Imperial Order of the Legion of Honour (), is the highest and most prestigious French national order of merit, both military and Civil society, civil. Currently consisting of five cl ...

. He was also vice-president of the Société Française des Électriciens and president of the

Société Mathématique de France Groupe Lactalis S.A. (doing business as Lactalis) is a French multinational dairy products corporation, owned by the Besnier family and based in Laval, Mayenne, France. The company's former name was Besnier S.A. Lactalis is the largest dairy pr ...

References

External links

*Annales.org
Alfred-Marie Liénard
{{DEFAULTSORT:Lienard, Alfred Marie French electrical engineers École Polytechnique alumni Mines Paris - PSL alumni Corps des mines 1869 births 1958 deaths French physicists French engineers

See also

References

External links