FromHow CDs Work , you learn that a normal CD uses microscopic bumps to store data . The control surface of the CD is a mirror , and the gibbosity interrupt the mirror ’s perfect airfoil . The laser that reads the CD can notice the remainder between a everlasting mirror and an imperfection have by a bump because of the deviation in reflectiveness . By interpreting " perfect mirror " as a " 1 , " and " bump " as a " 0 , " it is easy to storedigital informationon a cadmium . The protrusion on a compact disk are molded into the charge card when it is manufactured , so they are permanent .
To make a writeable compact disc ( CD - R ) , you need to modify the surface of a CD so you’re able to burn data onto it , turning it into a CD - R. There are no bumps on a CD - R. Aclear dye layercovers the CD ’s mirror . Awrite laserheats up the dye layer enough to make it unintelligible . Theread laserin a CD player senses the difference between clean dyestuff and opaque dye the same means it senses jut – it picks up on the difference in reflection factor .
To create arewriteable CD(CD - RW ) , you need a dyestuff layer that can be changed back and forth between opaque and transparent . This page talk about the exceptional material that CD - RW ’s usance . The material has the holding that it can interchange its transparency depending on temperature . wake to one temperature , the stuff cools to a pellucid state ; heat up to another temperature , it chill to a cloudy commonwealth . By exchange the power ( and therefore the temperature ) of the writing optical maser , the data on the certificate of deposit can be changed , or " rewritten . "
A compact disk - roentgen can be read by just about any candle player . atomic number 48 - RW phonograph record are not so various – lots of old candle musician can not show them .
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