Short info about DVD.

1. Dvd Digital Versatile Disc Presented By Ehtisham Ali

2. What is DVD? A DVD is a disc that is used for storing information that a computer can read. This can be a movie, music, television program or a computer game. DVDs look like compact discs as they are the same size but they store much more information in a different way.

3. Who invented it? The DVD was not invented by one person or company. Toshiba, Philips, Sony, and Matsushita Electric all helped to develop the technology used to make DVDs.

4. How does it get power? A DVD player is powered by electricity. It reads the data on the media using a light called a laser.

5. ? How does it work? DVDs are of the same shape 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 held in the form of small pits and bumps on the disc. A DVD is made of several layers of plastic. Each layer is made by injection molding plastic. This forms a disc that has tiny bumps arranged as a single very long spiral track of data. More on the bumps later.

6. ? How does it work? CONTD… 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.

7. How dangerous is it? The DVD is not dangerous by itself unless it is broken. Then the pieces are very sharp and could cut your fingers - or your feet if you step on them.

8. What does it do? It records digital information that can be used by a DVD player or computer.

9. How does it vary? The first DVDs could store around 4.5 Gigabytes, but later scientists found a way to make more layers so they could store more data. These are called "double layer" DVDs. But now there are two new types of DVDs called blu-ray and HD-DVD that store even more.

10. How has it changed the world? The DVD has modernized the current generations of video playing devices into the digital age.

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