File:Edison effect bulbs.jpg
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English: Bulbs Thomas Alva Edison used to discover thermionic emission (the Edison Effect) in 1884. They consists of an Edison incandescent lamp - an evacuated glass bulb with a hairpin shaped bamboo carbon or platinum filament - with an additional platinum foil electrode (center, inside the filament) connected to wire terminals. A current is applied to the filament, heating it. Edison found when he connected an ammeter between the filament and the auxiliary electrode, a current would flow, passing through the evacuated space of the bulb from filament to electrode. This current was later found to consist of electrons. This effect is the basis of vacuum tube technology, which dominated electronics for 50 years, until the 1970s. The 2nd and 4th bulb have two auxiliary electrodes, used to investigate how the current varied with distance from the filament. The 5th has two crossed bamboo filaments. Alterations to image: removed captions, cropped out one bulb that looked like it had a short circuit, and reformatted images from two rows to one. |
| Date | or earlier |
| Source | Retrieved 17 August 2013 from Clayton H. Sharp (January 1922) The Edison Effect and its Modern Applications, Journal of the AIEE, Vol. 41, No. 1, American Institute of Electrical Engineers, New York, p. 69, fig. 2, 10-c on Google Books |
| Author | Clayton H. Sharp |
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This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See this page for further explanation.
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
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| current | 04:48, 5 November 2013 | | 1,312 × 542 (224 KB) | Chetvorno (talk | contribs) | User created page with UploadWizard |
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