Edison effect (thermionic emission)
Efecto Edison (emisión termoiónica)
- Date
- 1880-1883 · confidence medium
- Place
- Menlo Park, New Jersey, United States
- Credited to
- Thomas Edison (preceded by Frederick Guthrie)
- Field
- Matter & energy
⚠️ Disputed: the sources disagree.
What was discovered
Edison observed that, in a bulb with a metal plate, a current flowed from the hot filament to the plate through the vacuum. It was the first observation of thermionic emission, the basis of the vacuum tube.
Frederick Guthrie had seen in 1873 that a red-hot iron sphere loses negative charge. Edison recorded it in 1880 and patented a voltage indicator in 1883, without grasping its scope.
What it led to
- Fleming's diode (1904) and De Forest's triode (1906)
- vacuum-tube electronics
- hot-cathode cathode-ray and X-ray tubes