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Transcript of period7pitts
As a cd spins a laser shines on the underside of the disc through the plastic and follows a spiril. The metal coating acts like a mirror and reflects the beam. The power of the reflection changes as the beam enters and leaves the pit. The electric signal (made to produce sound) is formed.
Usually a cd that does not play properly is almost always caused by dust, dirt, hair, fingerprints, scratches, or any other substance on the disc that can interfere with the laser reading the disc, causing it to skip.
How do cds work?
During playback the number of times a cd spins decreases from 500 to 200 revolutions per minute. This helps it to keep a constant scanning speed.