Object Details
- associated user
- unknown
- Edison, Thomas Alva
- Description (Brief)
- Two bamboo filaments with copper-clad connectors, no base, platinum element, round label on envelope. This early Edison lamp contains a metal plate mounted between the legs of the bamboo filaments. Edison's lamps (and all incandescent lamps since) suffered from an problem known as "lamp blackening" in which material evaporated from the filament and deposited on the inner-wall of the glass bulb. The metal plate was intended to catch some of the carbon particles. In 1883 an assistant was experimenting with this new device and electrically connected the metal plate to the positive and then the negative side of the lamp filament. (Remember, Edison was working with direct current.) To everyone's surprise a current was detected flowing through the vacuum inside the lamp between the filament and the plate.
- This became known as the Edison Effect and was put to use by Edison in the design of an electrical meter (US patent #307,031), though exactly how the Effect worked remained unclear. However, in 1890 John Ambrose Fleming performed a series of experiments and ultimately developed an understanding of the Effect. In 1904 he turned this understanding into a detector of radio signals - a "thermionic valve" that became the first radio tube. The discovery of the Edison Effect led to the development of practical radio tubes and electronic circuits. This technical innovation helped fuel the tremendous expansion of radio in the years following the First World War.
- Location
- Currently not on view
- Credit Line
- from International Business Machines, Inc., William J. Hammer Collection
- ca. 1883
- ca 1883
- ID Number
- EM.320462.02
- accession number
- 241402
- catalog number
- 320462.02
- Object Name
- Electron Tube, Diode
- diode
- Other Terms
- Electron Tube, Diode; Electron Tubes
- Physical Description
- glass (overall material)
- metal (overall material)
- Measurements
- electron tube, diode: 18 cm x 5 cm; 7 3/32 in x 1 31/32 in
- See more items in
- Work and Industry: Electricity
- National Museum of American History
- Record ID
- nmah_707354
- GUID (Link to Original Record)
- https://n2t.net/ark:/65665/ng49ca746a5-3476-704b-e053-15f76fa0b4fa
