# Tesla's Coil (DD-405)

> A Tesla coil is a resonant transformer invented by Nikola Tesla around 1891. A capacitor discharges through a primary coil of a few turns, and the oscillating magnetic field induces current in a secondary coil of many turns; resonance between the circuits builds very high voltage at high frequency. At the top terminal the voltage ionizes air and throws sparks. The footage shows a Tesla coil discharging.

- Department: Science (also History)
- First published: 2024-12-03
- Last updated: 2024-12-03
- Permalink: https://detailenjoyer.com/case/teslas-coil/
- Author: Marcus Easterling (DetailEnjoyer), The Detail Department

## On the timeline

- **1891**: Tesla develops the Tesla coil

Full timeline: https://detailenjoyer.com/timeline/?case=teslas-coil

## Quick facts

- **DD-405-F01**: Nikola Tesla, about 1891. _(Write-up · Exhibit A (Inventor))_
- **DD-405-F02**: Primary and secondary. _(Write-up · Exhibit B (Circuits))_

## Write-up

A Tesla coil steps up voltage until the air itself sparks. Nikola Tesla invented it around 1891.

1. **Inventor**: Nikola Tesla, about 1891.
2. **Circuits**: Primary and secondary.
3. **Induction**: Magnetic coupling.
4. **Resonance**: Builds voltage.
5. **Sparks**: Air ionizes.

## Reel vs. record

- **Note**: None needed.

## Video: Tesla's Coil: A Tesla Coil Steps up Voltage Until the Air Itself Sparks

- Duration: 29.6 s · Published: 2024-12-03
- File: https://detailenjoyer.com/assets/videos/DDGq8BkOH0u.mp4

### Transcript

Did you know? Tesla coils work by generating high-voltage, high-frequency electricity using two coupled circuits, a primary and a secondary. The primary circuit includes a power source, a capacitor, and a coil. When the capacitor discharges, it sends current through the primary coil, creating a magnetic field. This field induces a current in the secondary coil via electromagnetic induction, significantly amplifying the voltage due to the secondary coil's higher number of turns. The resulting high-frequency alternating current travels to the terminal, where it ionizes the surrounding air. NOW YOU KNOW!

## Questions & answers

**Q: Who invented it?**  
A: 1891. _(Source: Write-up · Exhibit A (Inventor) · Wikipedia: Tesla coil)_

**Q: What couples the coils?**  
A: Fields. _(Source: Write-up · Exhibit B (Circuits) · Wikipedia: Tesla coil)_

**Q: Which coil has more turns?**  
A: Steps up. _(Source: Write-up · Exhibit C (Induction) · Wikipedia: Tesla coil)_

**Q: What makes sparks?**  
A: Breakdown. _(Source: Write-up · Exhibit D (Resonance) · Wikipedia: Tesla coil)_

**Q: What discharges into the primary?**  
A: Stored charge. _(Source: Write-up · Exhibit E (Sparks) · Wikipedia: Tesla coil)_

## Sources

- [Wikipedia: Tesla coil](https://en.wikipedia.org/wiki/Tesla_coil)

## Cite this case file

Easterling, Marcus. "Tesla's Coil." The Detail Department (DetailEnjoyer), case file DD-405, last updated Dec 3, 2024. https://detailenjoyer.com/case/teslas-coil/