Today CDs or DVDs are very common and one has to know that how does it work. The CDs or DVDs are generally used to hold the information or data. The data can text, audio ,video or it can be any file. They are used store the required data in the form of digital bits. CD stands for compact disc and DVD for Digital Video Disc , DVD can with hold large amount of information. CD consists of protective layer and aluminum sheet containing the data. When a beam of light from the laser which is present in the CD reader, strikes the disc by passing through grating glass and filter. The light now has central peaks and gets filtered . As the polarized beam of light hits the aluminum sheet , a vertically polarized light is detected by a photo detector, which signal as bit 1.If there no reflection of light ,due to destructive phase difference, the signal bit is 0.These data are transformed by a digital to analog converter , to get required the output data.
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