• A. The telephone
  • B. The light bulb
  • C. The phonograph
  • D. The dynamo

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Think of an invention that allows you to read in the evening without candlelight. Something you still find in almost every home today, even though the technology looks quite different by now.

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The correct answer is B. The light bulb.

On October 21, 1879, Thomas Edison demonstrated a practical working light bulb for the first time, featuring a carbon filament that burned for more than 13 hours. As DBNL describes: others had found a high-resistance filament lamp somewhat earlier, but for Edison it was not a standalone invention. It was merely one component of a larger system. He simultaneously developed an entire electrical distribution network, so that the light bulb would actually be usable for the general public.

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Edison and the light bulb: more than just a bulb

Thomas Edison (1847–1931) is popularly regarded as the inventor of the light bulb. But that image is only partially accurate, and the interesting part lies precisely in everything else that was happening alongside that bulb.

Not the only one, but the one who finished it

The Briton Joseph Swan was working on a functional light bulb at virtually the same time. In 1880, both patented their invention, leading to a legal dispute that was ultimately resolved through collaboration: in England, they jointly founded the company “Ediswan.” What set Edison apart was that he did not stop at the bulb itself. He also designed the generators, the wiring, and the meters to measure electricity consumption. On December 31, 1879, he illuminated the streets surrounding his laboratory in Menlo Park, New Jersey, with electric light. A public spectacle that stirred considerable excitement.

Menlo Park was regarded as the world’s first industrial research center, where dozens of engineers worked simultaneously on different components of the same problem. That system was the real invention — the bulb was the visible result.

The phonograph: what Edison was most proud of himself

Interestingly, Edison considered the phonograph, invented in December 1877, his greatest personal achievement. As Demodernetijd describes, he had already astonished the public with this device capable of recording and playing back sound. Yet it is the light bulb that forever linked his name to the concept of “inventor.” Not the phonograph, not telegraphy, but a bulb.

There is something bittersweet in the fact that Edison himself had a different preference than the one history assigned to him.

From filament to LED

The classic incandescent light bulb, which works by heating a metal filament until it glows, has largely disappeared from the European market. The EU phased out traditional incandescent bulbs due to their poor energy efficiency: the majority of the energy is lost as heat rather than light. LED bulbs are now the standard.

Edison’s famous quote, “Genius is one percent inspiration and ninety-nine percent perspiration,” actually fits the story behind the light bulb perfectly. He tested thousands of materials for the filament before settling on carbon. No magical insight — just systematic trial and error. Whether that quote genuinely originated with him or was attributed to him later? That, frankly, is less certain than is often suggested.

About the three distractors

The three incorrect answers — the telephone, the phonograph, and the dynamo — are all inventions that genuinely have a connection to Edison. That makes the question harder than it appears at first glance, because anyone who quickly associates “Edison” with phonograph and selects that option is not far off in terms of logic. Just not in terms of the correct answer.