What does CD stand for?
AnswerCompact disc
CD is short for compact disc, an optical disc format introduced in the early 1980s.
Tech · Facts & stats
CD facts & stats
7 fact-checked facts about compact discs, each with the reason behind it. 5 more are in today's round and join this page after it closes.
The basics
In CD-ROM, what does ROM stand for?
AnswerRead-only memory
A CD-ROM holds data that can be read but not changed.
Going deeper
At what sample rate is audio stored on a standard music CD?
Answer44.1 kHz
Audio CDs take 44,100 samples of the sound wave per second.
In which direction does a CD's spiral data track run?
AnswerFrom the center outward
A CD is read starting near the center hole and moving toward the outer edge.
What clear plastic makes up most of a CD?
AnswerPolycarbonate
A CD is a polycarbonate disc with a thin reflective metal layer and a protective lacquer.
Expert level
What kind of laser light does a CD player use?
AnswerInfrared
CD players use a laser with a wavelength of about 780 nm, just beyond visible red light.
A CD's data is stored as tiny pits. What are the flat areas between the pits called?
AnswerLands
The laser detects transitions between pits and lands, which are decoded as binary data.
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