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.
A harmonic is any of the integer multiplications of the fundamental frequency. The fundamental frequency (f) is known as the first harmonic, and 2f is known as the second harmonic, and so on. A highly useful application of harmonics is the Fourier analysis. harmonic is any of the integer multiplications of the fundamental frequency. The fundamental frequency (f) is known as the first harmonic, and 2f is known as the second harmonic, and so on. A highly useful application of harmonics is the Fourier analysis.