Model railroad type example Sn3.5 is as follows, S (scale) being the prefix to n (narrow gauge) followed by 3.5 (prototype track gauge in feet), 3 and 1/2 feet, or 42 inches, which in Sn3.5 equates to actual modeling track width of .649 - .672 thousandths, 16.5 - 17.1 mm.
Definition of harmonic. 1  1a : overtone; especially : one whose vibration frequency is an integral multiple of that of the fundamentalb : a flutelike tone produced on a stringed instrument by touching a vibrating string at a nodal point.
In physics, resonance is the tendency of a system to oscillate at maximum amplitude at certain frequencies, known as. the system's resonance frequencies (or resonant frequencies). At these frequencies, even small periodic driving forces. can produce large amplitude vibrations, because the system stores vibrational energy. When damping is small, the.