Edison Observes the Edison Effect: The Seed of Electronics
Thomas Edison was trying to stop his light bulbs from blackening. Carbon filaments threw off particles that darkened the glass. He sealed a metal plate inside the bulb to catch them. It didn't work. But when he connected the plate to a positive charge, current flowed through the vacuum. When negative, nothing. He had no idea why. He patented it anyway, called it the Edison effect, then moved on. Twenty years later, someone figured out he'd discovered electrons moving in one direction only. He'd built the first vacuum tube. Radio, television, computers — all of it required that one-way flow. Edison saw it as a failed fix for dirty bulbs.
February 13, 1880
146 years ago
Key Figures & Places
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