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.
Wednesday, January 31, 2007
How does A Toaster Work
How does it work?
A heating element in a toaster is most often a thick nichrome wire. Like most wires in any house, nichrome wire conducts electricity. But other wires are made of metals that are better conductors of electricity. That means that electricity is easily passed through the wire, which can help all sorts of things work. But nichrome wire can't deliver electricity as well as copper can. All the energy can't transfer down the nichrome wire, so instead it's energy becomes heat. This means the wire gets very very hot! The same kinds of heating elements are used in combination with a fan in household hair dryers. The heating elements heat up everything around them, including the bread. If the bread is close to the heating element for the right amount of time, it turns a light brown color and turns into toast. If it is heated too long, the toast will turn black and begin to smoke. Toasters are generally built so that they stop on their own, to prevent this from happening.
A pop up toaster causes the toast to "pop" up when it stops. The slots in the top of it hold the bread. When the bread is first added, a cage at the bottom of the slot holds it up, partway out of its slot. At first, the heating elements are not hot, because no electrical current is flowing through them. The black lever on the right can be pushed down, which lowers the bread all the way in, so that it is very near the heating elements. Two other important things happen as the lever is pushed down. First, with the lever pushed down, the toaster allows electricity to flow through the heating elements, which causes the bread to start toasting. Second, a spring is compressed, and a latch holds the lever in place at the bottom position. Even if a person lets go of the lever at this point, the latch will keep it in place, and the toast will continue toasting.
But it won't continue forever. The bread isn't the only thing being heated by the heating element: many parts of the toaster itself are also being heated up. One of these parts is the release mechanism. This part is designed to change its shape as its temperature increases. Eventually, the release mechanism heats up enough that the latch is released: this is what makes the popping sound. Once the latch is released, the spring quickly pulls up on the lever, which stops the flow of electric current and allows the heating element to begin cooling down. At the same time, the spring pulls up the cage at the bottom of the slots, pushing the toast up out of the slots, so that it is easy to remove from the toaster. The release mechanism can be set to release the latch at a higher or lower temperature, which will cause the toast to be darker or lighter.
Invention
It was invented in Great Britain by Crompton and Co.in 1893. A person had to turn the bread over to toast both sides and turn the machine off by hand. Charles Strite invented the pop-up toaster in 1919.
Power Supply
Electricity provides the energy the toaster needs. When electric current flows through the coils of wire inside the toaster, they become so hot that they glow red. These glowing red wires are called heating elements.
Dangers
Because it uses electricity a toaster can be dangerous around water. Although it can be tempting to remove a stuck piece of toast with a knife, it is extremely dangerous to put anything metal into a toaster because the element can conduct electricity to the metal and to the person holding it. Because it gets very hot, you can burn yourself if you get too close to the elements.
Toaster has made the morning breakfast a little warmer and tastier and quick in this very fast World.
A heating element in a toaster is most often a thick nichrome wire. Like most wires in any house, nichrome wire conducts electricity. But other wires are made of metals that are better conductors of electricity. That means that electricity is easily passed through the wire, which can help all sorts of things work. But nichrome wire can't deliver electricity as well as copper can. All the energy can't transfer down the nichrome wire, so instead it's energy becomes heat. This means the wire gets very very hot! The same kinds of heating elements are used in combination with a fan in household hair dryers. The heating elements heat up everything around them, including the bread. If the bread is close to the heating element for the right amount of time, it turns a light brown color and turns into toast. If it is heated too long, the toast will turn black and begin to smoke. Toasters are generally built so that they stop on their own, to prevent this from happening.
A pop up toaster causes the toast to "pop" up when it stops. The slots in the top of it hold the bread. When the bread is first added, a cage at the bottom of the slot holds it up, partway out of its slot. At first, the heating elements are not hot, because no electrical current is flowing through them. The black lever on the right can be pushed down, which lowers the bread all the way in, so that it is very near the heating elements. Two other important things happen as the lever is pushed down. First, with the lever pushed down, the toaster allows electricity to flow through the heating elements, which causes the bread to start toasting. Second, a spring is compressed, and a latch holds the lever in place at the bottom position. Even if a person lets go of the lever at this point, the latch will keep it in place, and the toast will continue toasting.
But it won't continue forever. The bread isn't the only thing being heated by the heating element: many parts of the toaster itself are also being heated up. One of these parts is the release mechanism. This part is designed to change its shape as its temperature increases. Eventually, the release mechanism heats up enough that the latch is released: this is what makes the popping sound. Once the latch is released, the spring quickly pulls up on the lever, which stops the flow of electric current and allows the heating element to begin cooling down. At the same time, the spring pulls up the cage at the bottom of the slots, pushing the toast up out of the slots, so that it is easy to remove from the toaster. The release mechanism can be set to release the latch at a higher or lower temperature, which will cause the toast to be darker or lighter.
Invention
It was invented in Great Britain by Crompton and Co.in 1893. A person had to turn the bread over to toast both sides and turn the machine off by hand. Charles Strite invented the pop-up toaster in 1919.
Power Supply
Electricity provides the energy the toaster needs. When electric current flows through the coils of wire inside the toaster, they become so hot that they glow red. These glowing red wires are called heating elements.
Dangers
Because it uses electricity a toaster can be dangerous around water. Although it can be tempting to remove a stuck piece of toast with a knife, it is extremely dangerous to put anything metal into a toaster because the element can conduct electricity to the metal and to the person holding it. Because it gets very hot, you can burn yourself if you get too close to the elements.
Toaster has made the morning breakfast a little warmer and tastier and quick in this very fast World.
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