How do cds play music?

Answer 1

The disc has microscopic bumps impressed on a thin metal layer and protected by clear plastic.

The bumps are arranged as a sprial and can be read by shining a laser light onto them.

The laser light reflecting back from the disc, is read by a photo detector. The flickering light is decoded as either a 1, or a 0, and form binary data.

The information picked up, is also used to drive servo motors which keep the laser unit tracking the correct place on the disc, as it spins.

Audio CDs are optical discs that contain binary data. On most CDs, the data is encoded as two streams of 16-bit numbers which represent the audio waveforms of a left and right channel. The 16-bit numbers define points on the waveforms at a rate of 44,100 samples per second, which is fast enough to capture the highest frequencies that humans can hear. A CD player converts the stream of numbers to an electrical waveform by means of a digital-to-analog (D/A) converter. The electrical waveform can then be amplified to drive speakers or headphones.