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Mihajlo Idvorski Pupin was a Serbian-American physicist and electrical engineer. He was born in Idvor, Austria-Hungary (now Serbia) in 1854. He moved to the United States in 1874 and became a naturalized citizen in 1883. He is best known for his work on the transmission of telephone signals over long distances. He also invented the Pupin coil, which is used to amplify signals in telephone lines.