Quartz crystal oscillator of a watch The tuning fork shaped crystal vibrates at a specific frequency when exposed to an alternating electric current. Such crystals are used as timers in quartz watches. The interaction of the electrical and mechanical properties of a material is known as the Piezoelectric effect.

Oscillations are very common in everyday life with familiar examples being the motion of pendulum of a clock, quartz crystal in a watch, a tuning fork, the strings of guitar or a violin. Buildings and bridges vibrate when heavy trucks pass or when the wind speed is very high. Electrical oscillations occur in radio waves and at the atomic level atoms vibrate within a molecule.

Oscillations are also important in biological systems such as neural oscillations. Neural oscillation is rhythmic or repetitive neural activity in the central nervous system. Oscillations in membrane potential or rhythmic patterns of action potentials in neurons produce oscillatory activation of post – synaptic neurons. The synchronized activity of large numbers of neurons can give rise to macroscopic oscillations, which can be observed in the electroencephalogram (EEG). As oscillations are so common in everyday life the understanding of oscillatory motion is very important.

Vibrations give rise to waves such as water waves in ocean, waves in a sting and sound waves. The source of sound waves is a vibrating object and the detector of sound waves like ear drum or microphone also vibrates. When a wave travels through the medium, the medium vibrates.