How many years old when thomas alva edison invented first electric bulb?
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The first successful test was on October 22, 1879; it lasted 13.5 hours. Edison continued to improve this design and on November 4, 1879, filed for U.S. patent 223,898 (granted on January 27, 1880) for an electric lamp using "a carbon filament or strip coiled and connected to platina contact wires".
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