In 1960, the scientific community made an unusual decision: they named a unit of measurement after a man who had died in poverty, largely forgotten, in a New York hotel room. Today, the tesla (T) is fundamental to everything from MRI machines to electric vehicles.
Who Was Nikola Tesla?
Born in 1856 in modern-day Croatia, Tesla was an inventor, electrical engineer, and visionary who contributed to the development of alternating current (AC) electrical systems.
His rivalry with Thomas Edison—the "War of Currents"—shaped the modern electrical grid. Tesla's AC system won, and it's what powers your home today.
But Tesla's interests went far beyond power distribution. He worked on wireless energy transmission, radio (he held the patent before Marconi), X-rays, and even concepts resembling radar. Many of his ideas were decades ahead of their time.
The Unit: What Is a Tesla?
The tesla measures magnetic flux density, also called magnetic field strength. One tesla equals one weber per square meter, or equivalently, one kilogram per ampere per second squared.
In practical terms:
- Earth's magnetic field: 25-65 microtesla (μT)
- Refrigerator magnet: 5 millitesla (mT)
- MRI machine: 1.5-3 tesla
- Strongest continuous magnetic field created: 45.5 tesla
- Strongest pulsed magnetic field: over 1,200 tesla
Why Tesla?
The choice to honor Tesla recognized his foundational work with electromagnetic fields. His invention of the AC induction motor and transformer designs relied on deep understanding of magnetic fields.
Before the tesla, magnetic flux density was often measured in gauss (named after mathematician Carl Friedrich Gauss). The conversion is straightforward:
1 tesla = 10,000 gauss
The gauss remains common for weaker fields—Earth's field is about 0.25-0.65 gauss—while tesla is preferred for stronger fields in scientific contexts.
Tesla in Modern Technology
The unit bearing his name appears everywhere:
Medical Imaging: MRI machines are rated in tesla. A 3T MRI produces images with more detail than a 1.5T machine, though both use magnetic fields vastly stronger than anything Tesla himself could have generated.
Particle Physics: The Large Hadron Collider uses superconducting magnets producing up to 8.3 tesla to bend particle beams around its 27-kilometer ring.
Electric Vehicles: Motors in electric cars use permanent magnets and electromagnets measured in tesla. (Yes, Tesla cars use teslas.)
Data Storage: Hard drive read/write heads operate in magnetic fields measured in tesla.
The Forgotten Genius
Tesla died in 1943 with little money and few friends. He spent his final years feeding pigeons in New York parks and making increasingly eccentric claims about death rays and interplanetary communication.
Yet within 17 years of his death, the international scientific community named a fundamental unit after him—recognition that his contributions to understanding electromagnetism were invaluable.
The Numbers
Common conversions involving the tesla:
- 1 T = 10,000 gauss (G)
- 1 T = 1 Wb/m² (weber per square meter)
- 1 T = 1 kg/(A·s²)
- 1 mT = 10 G
- 1 μT = 0.01 G
Legacy
The tesla unit ensures that Nikola Tesla's name is spoken in laboratories, hospitals, and engineering firms worldwide, every single day. It's a fitting memorial for a man who wanted to give the world wireless free energy but settled for changing how we understand magnetic fields.
The next time you have an MRI scan, you're quite literally inside a tesla—honoring a Serbian-American inventor who imagined our electromagnetic future a century before it arrived.