Edison Effect lamp
date: label: Date made
content: 1883
label: date made
content: ca. 1883
label: date made
content: ca 1883
name: label: associated person
content: Edison, Thomas Alva
label: maker
content: Edison, Thomas Alva
label: maker
content: Edison, Thomas Alva
notes: label: Description (Brief)
content: This early Edison lamp contains a metal plate mounted between the legs of the bamboo filament. 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.
label: Description (Brief)
content: 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.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
creditLine: label: Credit Line
content: from International Business Machines, Inc., William J. Hammer Collection
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.320462.01
label: catalog number
content: 320462.01
label: accession number
content: 241402
objectType: label: Object Name
content: diode
label: Other Terms
content: Edison-Effect Lamp; Electron Tubes
physicalDescription: label: Measurements
content: overall: 7 in x 3 in; 17.78 cm x 7.62 cm