The groove is like a valley - each side of the valley represents one channel. The stylus vibrates in two orthogonal directions in response to the signal on each side. A moving magnet at the other end of the stylus is detected by two coils to give two channels (stereo)
Vinyl Groove
There are other variations like Moving Coil but essentially they operate in a mechanically similar way. There are of course more details such as RIAA equalization but the above explains the principles.
As for a redbook CD - there is NO mechanical analogy. Pits are read from a shiny spinning disc and translated to a digital signal that includes encrypted two channel sound sampled at 44.1 Khz. The encryption is Solomon-Reed interleave and allows for robust data error recovery by including about 10% extra redundant info that can be used to completely recover the actual data even given that any physical medium will get scratched and damaged.
Vinyl Groove
There are other variations like Moving Coil but essentially they operate in a mechanically similar way. There are of course more details such as RIAA equalization but the above explains the principles.
As for a redbook CD - there is NO mechanical analogy. Pits are read from a shiny spinning disc and translated to a digital signal that includes encrypted two channel sound sampled at 44.1 Khz. The encryption is Solomon-Reed interleave and allows for robust data error recovery by including about 10% extra redundant info that can be used to completely recover the actual data even given that any physical medium will get scratched and damaged.