# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DZaVgDBAOo9
- **Gondola URL:** https://gondola.cc/posts/66591652-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/fc2ee992cc.jpg
- **Posted:** 2026-06-10T16:08:03.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

In 1893, at the World’s Columbian Exposition in Chicago, Nikola Tesla stood a copper egg upright on its end without touching it. No glue, no tricks, no flattened base. A rotating magnetic field did the work that Columbus once did with a tap.

The legend says Columbus silenced his critics by standing an egg on its tip after cracking the shell flat. Tesla wanted to silence his own critics, the ones who doubted alternating current, and he did it with physics instead of force.

Beneath a wooden platform sat a toroidal iron core wound with coils. Tesla fed them two-phase AC: two currents offset by 90 degrees in time, through windings offset by 90 degrees in space. The result is the heart of his entire legacy, a magnetic field of constant magnitude that sweeps in a circle at synchronous speed, ω = 2πf.

The copper egg felt that sweeping field as changing flux. By Faraday’s law, the change drove eddy currents in the metal. By Lenz’s law, those currents fought the change, and the interaction produced torque. The egg became a rotor. The platform became a stator. The whole thing was an induction motor with no shaft and no contact.

A few details make it elegant:

	•	Copper is non-magnetic, so nothing was being pulled. Every bit of motion came from induced current alone.
	•	The egg must lag the field. At perfect sync there is no relative motion, no induced EMF, no torque. Slip is mandatory.
	•	As spin built, gyroscopic rigidity lifted the egg onto its long axis, balancing it on end like a spinning top.

This was not a parlor trick dressed as science. It was science dressed as a parlor trick, engineered to sell a nation on AC.

Tesla didn’t stand the egg up. He taught the field to do it.

#stemantics #nikolatesla #electromagnetism #inductionmotor #engineeringhistory

## Stats

- **Views:** 12,358
- **Likes:** 238
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## Tags

nikolatesla, inductionmotor, engineeringhistory, electromagnetism, stemantics

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