(c) Dr Paul Kinsler. [Acknowledgements & Feedback]

This is part of an information maze -- see the index-file for the full picture.

Waves

Waves are objects that are the opposite of particles - instead of being infinitesimally tiny objects at a particular point in space, they are spread out, and behave in an oscilliatory fashion.

    ,,,+++'''''+++,,,,,+++'''''+++,,,,,+++'''''+++
 
    ,,,++++''''''++++,,,,,,++++''''''++++,,,,,,+++
 
    ,,,++++'''''''++++,,,,,,,++++'''''''++++,,,,++
 
                    some _waves

Think of the circular ripples on the surface of a still pond after a pebble is dropped into it. Those ripples are a wave. Think of the vibrations of a guitar or violin string. The way the string oscillates rapidly up and down tells us it is like a wave. The guitar string vibrates and makes the air molecules vibrate in sympathy, and the sound that it makes is also a wave. Atoms in solids also can vibrate, and these vibrations can be described as phonons.

Waves are described by their wavelength and their frequency. The wavelength is related to the energy in the wave, and also its momentum. The ripples on water and sound waves are all travelling in a particular direction, and so the wave carries momentum. Some waves are stationary, such as the vibration on a guitar string - but this can be regarded as a combination of two waves identical travelling in opposite directions. Many types of wave can have any wavelength or energy, but some have minimum or maximum allowed values. The frequency of a wave is how many oscillations it undergoes per second.

For clarity, it is best to imagine a wave as having significant extent and always oscillating at the same rate - making it very much the opposite of a particle. However, "wave" is often used to mean more general oscillating behaviour - such as its use in my examples of water waves and sound above. These more typical uses are best described as wave-packets.

MATHS: The simplest mathematical function that can be used to describe a wave are the sine or cosine functions - both of these oscilate up and down in a very regular way.

XINDEX: wave-packet, wave-function, uncertainty-principle, uncertainty-principle, quantum-mechanic, quantum-confine, proton, particle, optical-cavity, neutron, light, index-file, hole, electron, electro-magnetic-waves, electro-magnetic-field, boson, atom, index-file.

19981021 1996xxxx (c) Paul Kinsler

XKEYWORD: wave

Email Feedback: Dr.Paul.Kinsler@physics.org

LOGBUG