A normal mode of an oscillating system is a pattern of motion in which all parts of the system move sinusoidally with the same frequency and with a fixed phase relation. The motion described by the normal modes is called resonance. The frequencies of the normal modes of a system are known as its natural frequencies or resonant frequencies. A physical object, such as a building, bridge or molecule, has a set of normal modes that depend on its structure, materials and boundary conditions.
When relating to music, normal modes of vibrating instruments (strings, air pipes, drums, etc.) are called "harmonics" or "overtones".
The most general motion of a system is a superposition of its normal modes. The modes are normal in the sense that they can move independently, that is to say that an excitation of one mode will never cause motion of a different mode.
The concept of normal modes also finds application in wave theory, optics, quantum mechanics, and molecular dynamics.
Read more about Normal Mode: Mode Numbers, Nodes, Coupled Oscillators, Standing Waves, Elastic Solids, Quantum Mechanics, Earth
Famous quotes containing the words normal and/or mode:
“We have been weakened in our resistance to the professional anti-Communists because we know in our hearts that our so-called democracy has excluded millions of citizens from a normal life and the normal American privileges of health, housing and education.”
—Agnes E. Meyer (1887–1970)
“A man of genius has a right to any mode of expression.”
—Ezra Pound (1885–1972)