While conversion of electrical energy to light was demonstrated in laboratories as early as 1801 by English scientist Humphry Davy, it took more than 100 years for the modern form of electric light bulb to be developed, with the contributions of many inventors.
The first successful incandescent light bulb was made by the British inventor Sir Joseph Swan in 1860 using a carbon paper filament, but it burned out very quickly.
In 1879, American inventor Thomas Edison created the first incandescent light bulb with the characteristics we recognize today using a carbon filament in an oxygen-free bulb. The first bulbs he experimented with lasted about 40 hours, but he eventually produced a bulb that could produce light for over 1500 hours.
How does it get power?
Electricity flows through wires to the bulb's socket. This power source may be a battery (as in a flash light) or a distant power plant supplying your local electric utility.
How does it work?
Electricity flows through a thin wire in the lightbulb called the filament. The filament used in a bulb has a property called "resistance." Resistance is the amount of friction that an object will put against electricity flowing through it. A filament has a lot of resistance to electricity.
Therefore as a result of this, the filament heats up and starts glowing, converting electrical energy to light energy. This is because of the Joule-effect, which means that resistances heat up when electrical current runs through them.
How dangerous is it?
Light bulbs themselves, if used properly, are not dangerous. Although their primary function is to produce light energy, as a side effect they also produce heat.
Light bulbs are sold according to the number of watts they use - the higher the number, the brighter the bulb is, and the more energy it uses. Despite getting hot, lightbulbs don't explode. However, the outer glass of a light bulb which has been on for some time is quite hot, and can cause minor burns, or the broken edges might cut the skin.
After hundreds of hours of operation the filament in the bulb eventually burns out and the light bulb no longer works. The light bulb then needs replacing. It is necessary to be careful in replacing the lightbulb. First, the switch for the light fixture needs to be turned off or the cable disconnected. This is because electricity flowing into the socket where the metallic part of bulb sits can give you a severe electric shock if you touch the inside of the socket or the metal base of the bulb while it is still partly in the socket. In addition, if the glass breaks it is possible to get cuts.
These hazards can be reduced by ensuring the bulb is cool to the touch before grasping it and by holding it firmly but not squeezing by the fattest part of the glass while rotating counter-clockwise until it comes completely loose
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