File:Edison effect bulb 1.jpg

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DescriptionEdison effect bulb 1.jpg	English: One of the bulbs Thomas Alva Edison used to discover thermionic emission (the Edison Effect) in 1884. It consists of an Edison incandescent lamp - an evacuated glass bulb with a hairpin shaped bamboo carbon 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.
Date	before 1922 date QS:P,+1922-00-00T00:00:00Z/7,P1326,+1922-00-00T00:00:00Z/9
Source	Downloaded August 17, 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

Public domain	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.	United States
	This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the rule of the shorter term for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See Wikipedia:Public domain and Wikipedia:Copyrights for more details.