# Get the Knowledge that sets you free...Science and Math for K8 to K12 students

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## Oscillations

Are you prepared for an earth quake? The 'Quake Alarm' saves valuable lives by removing the guesswork in earthquake detection. It is capable of detecting large earthquakes that occur hundreds of miles away and can detect moderate to minor earthquakes for many miles around any local area. It is designed to detect the first to arrive wave (P‐wave) to warn about the on–coming destructive wave (S‐wave). The damage always occurs due to vibrant S–waves. These vibrations are nothing but oscillations that occur at an equilibrium position. Lets learn more of such oscillations in this topic.

## After completing the topic, the student will be able to:

• Define, understand and expand the concept of oscillations to everyday science.
• Extend the concept of oscillations to explore simple harmonic motion.
• Develop the equations of motion for simple harmonic motion and apply them to real world situations.
• Explore the nature of simple pendulum, its types, properties and relevance to everyday science.
• Damped harmonic oscillation and its characteristic properties.
• Understand and employ the concept of elastic deformation to every day science.
• Define, explore, illustrate and apply the concepts of stress, strain and Hooke's law to various daily life examples.
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

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.

Brain alpha waves of EEG Electroencephalograph (EEG) traces show brain alpha waves. Alpha waves are produced when a person is awake and relaxed, with the eyes closed.
Oscillations and equilibrium

Oscillation is the repetitive variation typically in time, of some measure about a central value. Oscillations occur when a system is disturbed from a position of stable equilibrium. This displacement from equilibrium changes periodically over time. Hence oscillations are said to be periodic and display periodic motion. Many kinds of oscillatory motion are sinusoidal in time and are referred to as being simple harmonic motion(SHM).

A body that undergoes periodic motion always has a stable equilibrium position. When it is moved away from this position and released, a force called restoring force pulls it back towards equilibrium. When it tries to get there, it picks up some kinetic energy and overshoots. It stops somewhere on the other side and is again pulled back towards equilibrium.