Caption

Scanning electron micrograph (SEM) of the surface of a long-playing record (L.P.), showing the concentric grooves. The L.P. is made by pressing the recording information onto a softened (by heating) PVC disc. The blank area (centre) is the interval between 2 tracks: note the dust particles. The stylus (an elliptical or spherical diamond) sits nicely in the V-shaped groove, and lateral vibrations are picked up by the stylus and transduced by a moving coil or moving magnet cartridge into an electrical signal, which passes through an amplifier to be heard on loudspeakers. Magnification: X 8 at 35mm size, X 56 at 8x10-inch size.