Moritz Hermann von Jacobi (; 21 September 1801 – 10 March 1874), also known as Boris Semyonovich Yakobi (), was a German-Russian

electrical engineer Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the l ...

and

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 ...

Motors

Jacobi began to study magnetic motors in 1834. In 1835 moved to

Dorpat Tartu is the second largest city in Estonia after Tallinn. Tartu has a population of 97,759 (as of 2024). It is southeast of Tallinn and 245 kilometres (152 miles) northeast of Riga, Latvia. Tartu lies on the Emajõgi river, which connects the ...

(now Tartu, Estonia) to lecture at Dorpat University. He moved to

Saint Petersburg Saint Petersburg, formerly known as Petrograd and later Leningrad, is the List of cities and towns in Russia by population, second-largest city in Russia after Moscow. It is situated on the Neva, River Neva, at the head of the Gulf of Finland ...

in 1837 to research the usage of

electromagnetic force In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interac ...

s for moving machines at the

Russian Academy of Sciences The Russian Academy of Sciences (RAS; ''Rossíyskaya akadémiya naúk'') consists of the national academy of Russia; a network of scientific research institutes from across the Russian Federation; and additional scientific and social units such ...

. He investigated the power of an electromagnet in motors and generators. While studying the transfer of power from a battery to an electric motor, he deduced the

maximum power theorem In electrical engineering, the maximum power transfer theorem states that, to obtain ''maximum'' external power from a power source with internal resistance, the resistance of the load must equal the resistance of the source as viewed from its ...

. Jacobi tested the output of motors by determining the amount of zinc consumed by the battery. With the financial assistance of

Tsar Nicholas I Nicholas I, group=pron (Russian language, Russian: Николай I Павлович; – ) was Emperor of Russia, List of rulers of Partitioned Poland#Kings of the Kingdom of Poland, King of Congress Poland, and Grand Duke of Finland from 18 ...

, in 1839 Jacobi constructed a 28-foot electric motor boat powered by battery cells, which carried 14 passengers on the

Neva The Neva ( , ; , ) is a river in northwestern Russia flowing from Lake Ladoga through the western part of Leningrad Oblast (historical region of Ingria) to the Neva Bay of the Gulf of Finland. Despite its modest length of , it is the fourth- ...

river against the current at three miles per hour.

Jacobi's law

''Circuit Diagram''
Power is being transferred from the source,
with

voltage Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), ...

''V'' and resistance ''R_S'',
to a load with resistance ''R_L'',
resulting in a current ''I''. ''I'' is simply
the source voltage divided by the total
circuit resistance

The law known as the

states: The transfer of maximum power from a source with a fixed internal resistance to a load, the resistance of the load must be the same as that of the source. This law is of use when driving a load such as an electric motor from a battery.

Electrotyping and telegraphy

In 1838 he discovered galvanoplastics, or

electrotyping Electrotyping (also galvanoplasty) is a chemical method for forming metal parts that exactly reproduce a model. The method was invented by a Prussian engineer Moritz von Jacobi in Russia in 1838, and was immediately adopted for applications in ...

, a method of making printing plates by

electroplating Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the redox, reduction of cations of that metal by means of a direct current, direct electric cur ...

. The way this works is analogous to a battery acting in reverse. The ''

stereotype In social psychology, a stereotype is a generalization, generalized belief about a particular category of people. It is an expectation that people might have about every person of a particular group. The type of expectation can vary; it can ...

'' was an impression taken from a form of movable lead type and used for printing instead of the original type. This technique is used in relief printing. He also worked on the development of the

electric telegraph Electrical telegraphy is Point-to-point (telecommunications), point-to-point distance communicating via sending electric signals over wire, a system primarily used from the 1840s until the late 20th century. It was the first electrical telecom ...

. In 1842-1845 he built a telegraph line between

and

Tsarskoe Selo Tsarskoye Selo (, , ) was the town containing a former residence of the Russian imperial family and visiting nobility, located south from the center of Saint Petersburg. The residence now forms part of the town of Pushkin. Tsarskoye Selo forms ...

using an underground cable. In 1867 he was a Russian delegate to the Commission on Measurement Units at the Paris

World's Fair A world's fair, also known as a universal exhibition, is a large global exhibition designed to showcase the achievements of nations. These exhibitions vary in character and are held in different parts of the world at a specific site for a perio ...

. He was a strong proponent of the

metric system The metric system is a system of measurement that standardization, standardizes a set of base units and a nomenclature for describing relatively large and small quantities via decimal-based multiplicative unit prefixes. Though the rules gover ...

Naval mine

In 1853 Jacobi developed the Jacobi naval mine. The mine was tied to the sea bottom by an anchor, a cable connected it to a

galvanic cell A galvanic cell or voltaic cell, named after the scientists Luigi Galvani and Alessandro Volta, respectively, is an electrochemical cell in which an electric current is generated from spontaneous oxidation–reduction reactions. An example of a ...

which powered it from the shore. The power of its explosive charge was equal to of

black powder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, charcoal (which is mostly carbon), and potassium nitrate, potassium ni ...

. Its production was approved by the Committee for Mines of the

Ministry of War of the Russian Empire Ministry of War of the Russian Empire (, ''Military Ministry'') was an administrative body in the Russian Empire from 1802 to 1917. It was established in 1802 as the ''Ministry of ground armed forces'' () taking over responsibilities from the C ...

. In 1854 60 Jacobi mines were laid in the vicinity of the Forts Pavel and

Alexander Alexander () is a male name of Greek origin. The most prominent bearer of the name is Alexander the Great, the king of the Ancient Greek kingdom of Macedonia who created one of the largest empires in ancient history. Variants listed here ar ...

(

Kronstadt Kronstadt (, ) is a Russian administrative divisions of Saint Petersburg, port city in Kronshtadtsky District of the federal cities of Russia, federal city of Saint Petersburg, located on Kotlin Island, west of Saint Petersburg, near the head ...

Family

Von Jacobi's brother was the mathematician

Carl Gustav Jacob Jacobi Carl Gustav Jacob Jacobi (; ; 10 December 1804 – 18 February 1851) was a German mathematician who made fundamental contributions to elliptic functions, dynamics, differential equations, determinants and number theory. Biography Jacobi was ...

. Jacobi was born into an

Ashkenazi Jewish Ashkenazi Jews ( ; also known as Ashkenazic Jews or Ashkenazim) form a distinct subgroup of the Jewish diaspora, that Ethnogenesis, emerged in the Holy Roman Empire around the end of the first millennium Common era, CE. They traditionally spe ...

family.Pieper, H. (2005). Der Euler des 19. Jahrhunderts: CG Jacob Jacobi. ''

Elemente der Mathematik ''Elemente der Mathematik'' is a peer-reviewed scientific journal covering mathematics. It is published by the European Mathematical Society Publishing House on behalf of the Swiss Mathematical Society. It was established in 1946 by Louis Loc ...

'', 60(3), 89-107.

Notes

External links

* * Calvert, J. B., "
Jacobi's Theorem
Also known as the Maximum Power Transfer Theorem, misunderstanding of it retarded development of dynamos''". March 30, 2001

Jacobi's motor - The first real electric motor of 1834 {{DEFAULTSORT:Jacobi, Moritz von 1801 births 1874 deaths German Ashkenazi Jews Emigrants from the Kingdom of Prussia to the Russian Empire Electrical engineers from the Russian Empire Inventors from the Russian Empire Demidov Prize laureates Full members of the Saint Petersburg Academy of Sciences Burials at Smolensky Lutheran Cemetery 19th-century engineers from the Russian Empire Sustainable transport pioneers