The Nature of Waves
Summary
- Definition
- A wave is a disturbance that propagates through a medium.
- verb, propagate; noun, propagation: refers to the transmission of a disturbance from one location to another.
- singular, medium; plural, media: refers to the intervening substance(s) through which a disturbance is transmitted.
- A wave is a disturbance that propagates through a medium.
- Essential property
- Waves transfer energy, momentum, and information, but not mass.
- Classifying waves by medium
- Mechanical waves
- Matter is the medium.
- Sound is a mechanical wave.
- Electromagnetic waves
- Electric and magnetic fields are the media.
- Light is an electromagnetic wave.
- Electromagnetic waves include, radio waves, microwaves, infrared, light, ultraviolet, x-rays, and gamma rays.
- Electromagnetic waves are dealt with more fully in another section of this book.
- Gravitational waves
- The gravitational field is the medium.
- Matter waves
- The quantum mechanical description of fundamental particles like electrons and quarks as a wave
- Mechanical waves
- Classifying waves by type of disturbance
- Transverse waves
- The disturbance is perpendicular to the direction of propagation.
- All electromagnetic waves are transverse. This includes light.
- A crest is a point of maximal change in the positive direction.
- A trough is a point of maximal change in the negative direction.
- Longitudinal waves
- The disturbance is parallel to the direction of propagation.
- Sound is a longitudinal wave.
- A compression or condensation is a region where the medium is under compression.
- A rarefaction or dilation is a region where the medium is under tension.
- Complex waves or surface waves
- A combination transverse-longitudinal wave that forms near the surface of some media
- Waves on water (deep water waves or tiny ripples) are complex waves.
- Torsional waves
- The disturbance causes the medium to twist.
- Are significant in some large structures like bridges and skyscrapers.
- Transverse waves
- Classifying waves by duration
- adjective: episodic, intermittent, sporadic; noun: pulse, burst, surge, spike, transient
- The disturbance is momentary and sudden.
- adjective: periodic, harmonic, oscillatory; noun: wave train
- The disturbance repeats continuously and at regular intervals.
- The next section in this book is all about periodic waves.
- adjective: episodic, intermittent, sporadic; noun: pulse, burst, surge, spike, transient
- Classifying waves by appearance
- Traveling waves…
- appear to move.
- Standing waves or stationary waves…
- do not appear to move.
- are dealt with in a separate section of this book.
- Traveling waves…