COMPUTER ARCHITECTURE
SECONDARY STORAGE DEVICES
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Pit
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Land
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Pit End
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Land End
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Detailed explanation-1: -The music on a CD is imprinted in the form of pits of varying length on a spiral track 3.52 miles (5.66 kilometres) long. There are approximately 16, 000, 000, 000 pits 0.11 micro-metres deep. The largest pit dimension is 3.054 microns; the smallest is 0.833 microns.
Detailed explanation-2: -Optical devices When the laser shines on the disc surface, lands reflect the light back, whereas pits scatter the laser beam. A sensor looks for the reflected light. Reflected light (lands) represents a binary ‘1’, and no reflection (pits) represents a binary ‘0’.
Detailed explanation-3: -A motor spins the disc, moving the pits past the light beam. When the light shines onto a land between pits, it is reflected back onto a photodiode, which is like a light meter. Each reflected pulse of light causes a burst of current.