And There Was Light

It is so normal to turn on a light every evening. The inventor Thomas Edison was the first one who made this possible with this generator. But we do not turn on our lights with this invention. What is up with that?

Por. Edison, Thomas. 1847-1931.LIFE Photo Collection

The purpose of the American inventor Thomas Edison was electric light in every household.

In 1879 he presented the light bulb. But good to know, at that moment there was no sight of an electricity network.

DC generator (1878/1890) by EdisonNEMO Science Museum

Edison could turn on the light with this direct current (DC) generator.

With two long black cylinders this generator got the nickname ‘the long-legged Mary-Ann’.

This is a small version of 50 centimeters from the collection of NEMO Science Museum. There are versions known of 2 meters high.

The lying ‘Jumbo’ versions are 3 meters (10 feet) long and used for the first central power station in New York.

The brown cylinder in the middle is the rotor. It rotates thanks to a steam engine for example. This effects a magnetic field at the stator.

The black part is the stator, with two long black cylinders. In these you will find field coils, which create the magnetic field and creates the current.

Six small rods, as you can see here next to each other, are the ‘brushes’ on the commutator. These collect the direct current.

From this generator comes a direct current (DC). Perfect for a light bulb, but it appeared to be not very efficient for an electricity network.

At the same time alternate current (AC) was invented and a so called ‘war on currents’ occurred. Edison lost the battle and now there is light with AC.

The inventor Edison helped us to get electric light, as this object shows. But we do not use this invention nowadays.

Credits: Story

Object of the month – June 2020
Every month NEMO Science Museum shows one of the 19,000 unique objects. An item that was used in everyday life in days gone by and that shows how technology has changed in the course of time.

This story is created with thanks to Han Noot.

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
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