Volts, watts, ohms… Our modern language owes part of the vocabulary related to the science of electricity to the surnames of its great inventors. Among them, one of the greatest, André-Marie Ampère, a Frenchman with a complex destiny, died in poverty, but his inventions transformed the world.
What are some key publications by Ampère?
Who was André-Marie Ampère?
Straddling two centuries, André-Marie Ampère was born in 1775 in Lyon and died in 1836 in Marseille. Although he began studying Latin at a young age under the guidance of his father, a silk merchant, he quickly developed an interest in mathematics and science, which his father continually supported.
Marked by the death of his sister and then his father, who was executed by the Revolutionary Tribunal, Ampère went through a period of depression from which he emerged through the discovery of botany, music, and poetry. He married Julie Caron in 1799 before becoming a professor of physics at the École centrale de l’Ain in Bourg-en-Bresse, despite not having a degree.
He then obtained a chair in mathematics and astronomy at Lyon, but his wife’s death from illness led to a second period of depression that was not alleviated by his second marriage.
He then moved to Paris to work as a tutor in mathematical analysis at the École polytechnique. After holding various positions, he taught at the Collège de France before being elected to the Academy of Sciences.
Investing all his money into his inventions, he remained poor and died in obscurity, while his discoveries revolutionized the scientific world.
⋙ Electric networks, “the weak link in the clean energy transitions”?
Galvanometer
The galvanometer is a device capable of measuring the amount of electricity carried by a very brief current. Before reaching this invention, André-Marie Ampère worked on the astatic compass, which consisted of two small magnets placed in opposite directions, eliminating the influence of the Earth’s magnetic field during movement.
It is a device whose high sensitivity is often used in zero methods, techniques that allow the comparison of quantities relative to a standard. The galvanometer is still used today to measure small amounts of current.
First Electric Induction Machine
In 1821, Ampère was in Geneva and closely approached the principle of induction, which is the creation of an electric current from and at a distance from another, a concept that would later lead to the development of dynamos and alternators.
Using a system of a coil and a strong magnet, he observed that the ring placed on his device was moved by the influence of the coil. However, it was Michael Faraday who would receive credit for the discovery in 1836, a fact that Ampère acknowledged while noting that he had indeed come close to the phenomenon.
Electromagnet: An Invention with Arago
After studying circular currents and inventing the solenoid, a device made of wires wound into a long helix that produces an electromagnetic field capable of making a magnet placed in the center rotate around its axis, Ampère went further with the electromagnet, which converts electrical energy into magnetic energy. This invention is still commonly used in industry today.
“Theoretical” Inventions
The invention of devices went hand in hand with reflection on the laws of physics. André-Marie Ampère went against the prevailing scientific ideas of his time by explaining the phenomenon of magnetism through the theory of molecular currents: tiny electrical particles would circulate within conductors. It would take the discovery of electrons 60 years later to confirm his theory.
Q/A on André-Marie Ampère
What is Ampère’s law?
Ampère’s law describes the magnetic field generated by an electric current. It states that the magnetic field around a closed loop is proportional to the electric current passing through the loop.
What is the SI unit of electric current named after Ampère?
The ampere (symbol: A) is the SI unit of electric current, named in honor of Ampère. It measures the flow of electric charge.
What is Ampère’s circuital law?
Ampère’s circuital law is a mathematical formulation of Ampère’s law, stating that the line integral of the magnetic field around a closed loop is equal to the current passing through the loop multiplied by the permeability of free space.