CDs/ compact discs are now a major and popular object to store any data. In a Compact Disc, music or any other data is stored in a digital way. This process is not very simple. First the data needs to be recorded then it is converted into binary numbers by a procedure known as sampling.
A sound turns into series of numbers at the rate of 44,100 times a second. The data or music converts into the binary system and is stacked one after another. That means every sound or data will be converted into one or zeroes and makes a long string of millions of ones and zeros. The CD players’ use a flashing laser light to record and read back this data and music.
The description of CD
The CD is a circular slim disc made up of metal and plastic. The diameter of a CD is just about 41/2 inches or 12 cm. Basically the CDs have three layers. The first layer is made up of polycarbonate it is a sort of tough brittle plastic. The middle layer is made up of thin aluminum and on the top; there is a coating of lacquer.
One part of the CD is shinny and the other part of the CD is dull. The shiny part is the most important part as this is the portion where all the data has been stored. The laser beam can bounce back and forth to read the information from a shinny part. This is the reason that data is recorded on the shiny surface of the disc. The dull part mainly has the details of the contents of the CD.
CD making procedure
Normally, CDs are made from a master disc. The CDs have bumps in it and the bumps are called pits. The master disc is burned with a laser beam that scratches pits into the surface. The pits represent the zero that means every time the laser burns a pit into the disc a zero stored there. The flat unburned area is called a land. The absence of bumps represents one. The laser stores the data from the master Disc to other discs by burning some areas and leaves some unburned areas.
This is the basic way of storing data from the master disc to other CDs. The disc holds this information in an invisible tight constant spiral of about 3-5 billion pits. Every pit absorbs an area about two millionths of a millionth of a square meter. In a CD making factory, the CDs are made from the master disc by burning data into the exterior of the disc. On the other hand when the CDs are played to read the data it works exactly in the opposite manner.
The advantages of CD
The basic advantages of the CDs are that they don’t need to be touched by anything while playing, only the laser beam touches harmlessly the exterior and thus it, doesn’t get scratched. That is why it can be used for a longer period. There is another advantage of the CD is that if someone wants he/she can instantly move the laser swiftly to any part of the disc thus one can jump from one data to another or from one song to another.
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