Bell’s greatest invention: the photophone

Nope. it was not about a webcam. In the 19th century they barely had working photo cameras let alone phones that would send images too. No, the photophone actually means that Alexander Graham Bell manages to get sound transmitted using light. Using light to send over sound 200 meters away was a remarkable achievement for his time and he was 100 years early.

Only now we use fiber optics to send over data, but Bell managed this in the 19th century. Ok, his setup was primitive, but he used a selenium plate, a drum with a mirror on its side and some lenses.

what happened was that the light would be directed at the drum with a flexible mirror on the side, and then Bell would speak into that drum. The mirror would then wobble and the light reflected by it would wobble too.

When this wobbling light hits the selenium plate, then a current is generated. the amount of wobbling generates sound of different frequencies and these electrical impulses are then converted into sound. It was astonishing: Bell managed to use light to send over sound 200 meters away. Too bad this did not became mainstream.

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