In physics,<unk>   is the tendency of a system to oscillate at larger amplitude at some frequencies than at others.  These are known as the system's<unk>  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<unk>  frequency is approximately equal to the natural frequency of the system, which is the frequency of free vibrations.  Resonant phenomena occur with all types of vibrations or waves: there is mechanical<unk> , acoustic<unk> , electromagnetic<unk> , Nuclear Magnetic<unk>  (NMR), Electron Spin<unk>  (ESR) and<unk>  of quantum wave functions.   Resonant systems can be used to generate vibrations of a specific frequency, or pick out specific frequencies from a complex vibration containing many frequencies.<unk>  was discovered by Galileo Galilei with his investigations of pendulums beginning in 1602.
Resonance
Deceleration
Character displacement
Anise
Mixture
Perspiration
Isotope separation
Dislocations