The stylus, or needle, is vibrated by the grooves in the LP, which moves magnets placed near a coil. The coil in turn generates electricity, which gets amplified into an audio signal.
And now vinyl enthusiast Ben Krasnow has taken it a step further by creating a stop-motion video of the needle moving through a record’s grooves, explaining how he used his electron microscope to image the record.
Source: IFL Science