1. The History of Lighting
Teachers: CristinaGrosu
Cristina Hapenciuc
Students: SamuelAndronache
Dumitru Ivancov
Valentin Padurariu
Bogdan Vasiliu
Technical College ‘Samuil Isopescu’ Suceava

2. Content summary: The first light sources used by humans.
The invention of the incandescent light bulb by Thomas Edison.
Improving the light bulb.
The halogen light bulb.

3. Introduction
People wanted to lighten up their homes since ancient times.
In order to do this, it was necessary to study the natural light sources and understand how they produce light, so that people could produce artificial light in a similar way.

4. The first light sources used by humans
FIRE – (it was used for the first time by burning the wood ) produces light , but it has some disadvantages because it requires large quantities of wood and produces a lot of smoke, which is very toxic.
One solution was to change the combustible , so people began to use other kinds of combustible such as wax and resin from which they made candles.
Candles require less combustible and produce more light and less smoke.

5. Gas lamp
In 1798 William Murdoch suggested other way of lighting based on gas burning. The first illuminated city using gas lamps was London in This new kind of lighting spread quickly across Europe and America.

6. Timisoara , the First European City with Public Street Lighting
Over time, Timisoara (city in West Romania) recorded several firsts. Besides the fact that the municipality is known as the first city in Romania in which horse-drawn trams circulated, in 1884, in Timisoara has also recorded a great premiere: it became the first European city with street lighting.

7. Improving the gas lamp
In 1885 baron Welsbach presented an incandescent gas mantle , which is a device for generating bright white light when heated by a flame.
This method had something in common with Edison’s researches. Both were using incandescence for lighting.
This kind of lighting was used for street lighting ,because of its toxic combustion gases until 1930.

8. The invention of the light bulb
In childhood Thomas Edison was afraid of darkness but he was very good at Physics and Chemistry , so he understood the great disadvantages of gas lamp lighting. When he grew up he worked hard to produce lighting using electricity.

9. To create the first electric light bulb , Edison used Jule’s thermoelectric effect , connecting a conductive filament to an electric source. The filament heats and if it reaches incandescence it will light up .
Edison’s first light bulb contained air in the glass globe and lightened up for a short period of time. Edison figured out that the filament burned because the air contained too much oxygen which maintained the burning.
Later Edison had to create a vacuum environment inside the light bulb to make it last longer.

10. IMPROVING THE LIGHT BULB
Later , sublimation phenomenon was discovered. When the light bulb lights , small parts of the hot wolfram filament sublimates (they turn into steam) so the filament gets thinner and the light bulb burns.
Sublimation is the transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase.
Sublimation is an endothermic phase transition that occurs at temperatures and pressures below a substance's triple point in its phase diagram.
To reduce the sublimation of the light bulb’s filament , they had to use nitrogen inside the glass globe so it could last longer.

11. Desublimation is also very important…
Desublimation is the process of matter changing from a gas to a solid.
Sometimes the used light bulbs are getting dark because wolfram’s vapours desublimate turning into small solid particles which deposit on the inner surface of the glass bulb darken their surface.

12. The halogen light bulb
The halogen light bulb or lamp is a type of incandescent lamp which uses a halogen gas in order to increase both light output and rated life. They are known for moderately high efficiency, quality of light and high rated life compared to regular incandescent lamps.
First lamp to use halogen gas (chlorine) was patented in 1882, but the first commercial halogen lamp that used iodine as a halogen gas was patented in 1959 by General Electric. It was developed by Elmer Fridrich and Emmet Wiley who worked at General Electric, in Since 1980, halogen lamp was improved and made lighter.

13. Webliography https://www.Wikipedia.com https://www.google.com