DVDs resemble compact discs as their physical dimensions are the same store much more information in a different format.DVD (also known as "Digital Versatile Disc" or "Digital Video Disc") is an optical disc that can be used for data storage, including movies with high video and sound quality.
Who invented it?
The invention of DVD cannot be attributed to any one person or company. Toshiba, Philips, Sony, and Matsushita Electric all had a hand in the technology used to make DVDs. The standards used in creating DVDs are maintained by DVD Forum.
How does it get power?
A DVD player is powered by electricity. It reads the data on the media using a light.
How does it work?DVDs are of the same diameter and thickness as CDs, and they are made using some of the same materials and manufacturing methods. Like a CD, the data on a DVD is encoded in the form of small pits and bumps in the track of the disc. A DVD is composed of several layers of plastic, totaling about 1.2 millimeters thick. Each layer is created by injection molding polycarbonate plastic. This process forms a disc that has microscopic bumps arranged as a single, continuous and extremely long spiral track of data. More on the bumps later.
Each writable layer of a DVD has a spiral track of data. On single-layer DVDs, the track always circles from the inside of the disc to the outside. That the spiral track starts at the center means that a single-layer DVD can be smaller than 12 centimeters if desired.
How dangerous is it?
The dvd is not dangerous by its self unless it is broken
What does it do?
It records digital information that can be accessed/used by a DVD player.
How does it vary?
DVDs are entering the next generation and now there are two new types of DVDs called bluray and HD-DVD.
How has it changed the world?
The DVD has modernized the current generations of video
Sunday, February 25, 2007
Tuesday, February 6, 2007
Dangers
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.
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.
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.
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.
Power supply
Power Supply
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.
what does a light bulb do?
It gives light by converting electrical energy into light energy.
Although we say the filament "burns out" it actually vaporizes over time. Some of it can be seen as darkening on the glass where it has solidified. The gas inside the glass envelope is Argon which is used because it is inert and therefore cannot unite with the filament.
Change created by Light Bulb in the World!!!
The lightbulb is probably one of the most significant inventions in science.
It has changed the world by letting people do work at night. Previously this was very hard to do because other light sources (such as candles or fires) did not provide enough light.
The full impact of the lightbulb is much larger than only reading or writing at night.
Travel: Night travel by automobiles has largely been made possible by the lightbulb. Also, light houses all over the world use very powerful light bulbs, and this provides the right guidance for all ships.
Medicine: All internal and non-intrusive medical procedures use variants of the original lightbulb.
Mining: Earlier, underground miners used torches, which also added to the carbon dioxide content in the air, and therefore made breathing difficult. With the advent of lightbulb, mining has also become healthier and safer. In carbon mines, the risk of explosion of the carbon powder contained in the air was so high that conventional fire lanterns couldn't be used (they used a tupid metal mesh covered lanterns), with lightbulbs carbon mining become safer.
Apart from this, the light bulb is used in various other fields including communications, sports, etc.
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.
what does a light bulb do?
It gives light by converting electrical energy into light energy.
Although we say the filament "burns out" it actually vaporizes over time. Some of it can be seen as darkening on the glass where it has solidified. The gas inside the glass envelope is Argon which is used because it is inert and therefore cannot unite with the filament.
Change created by Light Bulb in the World!!!
The lightbulb is probably one of the most significant inventions in science.
It has changed the world by letting people do work at night. Previously this was very hard to do because other light sources (such as candles or fires) did not provide enough light.
The full impact of the lightbulb is much larger than only reading or writing at night.
Travel: Night travel by automobiles has largely been made possible by the lightbulb. Also, light houses all over the world use very powerful light bulbs, and this provides the right guidance for all ships.
Medicine: All internal and non-intrusive medical procedures use variants of the original lightbulb.
Mining: Earlier, underground miners used torches, which also added to the carbon dioxide content in the air, and therefore made breathing difficult. With the advent of lightbulb, mining has also become healthier and safer. In carbon mines, the risk of explosion of the carbon powder contained in the air was so high that conventional fire lanterns couldn't be used (they used a tupid metal mesh covered lanterns), with lightbulbs carbon mining become safer.
Apart from this, the light bulb is used in various other fields including communications, sports, etc.
Invention
While conversion of electrical energy to light was demonstrated in laboratories as early as 1801, 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 succussful incandescent light bulb was made by the British inventor in 1860 Joseph Wilson Swan.
How does a light bulb work?
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. A filament has a lot of resistance electricity. Therefore as a result of this, the filament heats up and starts glowing. The filament converts electrical energy to light energy.
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. A filament has a lot of resistance electricity. Therefore as a result of this, the filament heats up and starts glowing. The filament converts electrical energy to light energy.
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