The electric motor it is one of the most revolutionary inventions in history, a turning point in the electrification of the world. At the center of this revolution is the rotating magnetic fieldthe fundamental principle that allows alternating current (AC) motors to operate. But who was responsible for this discovery? TO Galileo FerrarisItalian physicist and engineer, o Nikola Teslathe famous Serbian-American inventor?
The contribution of Galileo Ferraris
Galileo Ferraris (1847-1897) was full professor of technical physics at the Polytechnic of Turin, as well as senator of the Kingdom of Italy, for just three months, before dying on 7 February 1897 at the age of 49 due to pneumonia.
In 1885, he began studying the effects of rotating electromagnetic fields and their potential practical uses. In the March 1888Ferraris theorized the principle mathematically and officially published it in a note presented toAcademy of Sciences of Turin. The principle was based on the use of two currents alternating and out of phase with each other to generate a rotary movement. This principle was also demonstrated in the laboratory with a prototype asynchronous motor.
However, Ferraris considered the rotating magnetic field-based motor an academic exercise rather than a device with immediate practical applications. For this reason, he did not patent his discovery and shared it freely with the scientific community.

Nikola Tesla’s contribution
Almost at the same time, Nikola Tesla was working in the United States on a series of inventions related to alternating current. Tesla discovered the principle of the rotating magnetic field independently, about the same time as Ferraris. However, unlike the Italian, Tesla was strongly oriented towards commercializing his discoveries. In the May 1888Tesla patented an induction motor based on this very principle in the United States and presented his work at the American Institute of Electrical Engineers.
Tesla collaborated with the industrialist George Westinghousewho saw in his inventions the future of electricity distribution. This caused Tesla’s motor to become the center of the alternating current system that won the so-called “War of Currents” against Thomas Edison and direct current (DC).

The paternity dispute
The “controversy” arises from the near simultaneity of the discoveries. Both researchers arrived at the rotating magnetic field independently, but with different approaches and intentions:
- Ferraris he was the first to publish his discoveries (March 1888) but did not patent anything, considering the engine a purely scientific interest;
- Tesla instead he patented his induction motor a few months later, in the United States, where he had greater visibility and access to the industrial market.
Tesla, thanks to the support of Westinghouse, dominated the world scene as we know, while Ferraris remained in a more secluded position, still remaining today a figure little known to the general public. Ferraris himself, among other things, openly recognized Tesla’s work and his ability to carry forward the development of inventions related to the rotating field.
This attitude underlines not only the scientific greatness, but also the human one of Ferraris, which he preferred enhance scientific and collective progress rather than fueling personal competition. His belief that Tesla had arrived at his discoveries independently demonstrates the mutual respect between the two scientists and reflects the value of scientific dialogue as a driver for innovation.
In this context, the lack of rivalry highlighted by Ferraris contrasts with what is often a popular narrative focused on competitions and clashes between great minds. Their work, however, can be seen as a complementary contribution to building the foundations of modern electrical engineering.
But then who is the real inventor?
Following what has just been said we can therefore conclude that both can be considered the “fathers” of the rotating magnetic field. Ferraris is undoubtedly a precursor from this point of view scientificwhile Tesla is credited with making the discovery one practical reality and commercial.
Today, both Ferraris and Tesla are celebrated for their contributions. In Italy, Ferraris is considered a symbol of dedication to pure research, while Tesla is universally recognized as one of the most prolific and visionary inventors in history. The dispute between them does not obscure the fact that both played a crucial role in the development of the electric motor and the technological progress of the modern world.