Properties
- A wave is a disturbance that propagates through a medium.
- Propagation describes the spreading of a disturbance
- Waves transfer energy, momentum, and information, but not mass.
CLASSIFICATION
Classifying Waves by Medium
- Mechanical Waves: matter is the medium
- Electromagnetic Waves: electric and magnetic fields are the media
Light is an electromagnetic wave
- Gravitational Waves: the gravitational field is the medium.
Classifying Waves by Orientation
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Classifying Waves by Appearance
- Traveling Waves: appear to move
- Standing Waves: do not appear to move
Characteristics
- Amplitude (A) is the maximum absolute value of a periodically varying quantity.
- Amplitude has the unit of the quantity that is changing (ex. displacement, pressure, field strength, etc.)
- Period (T) is the time between successive cycles of a repeating sequence of events.
- T = t/n (time per number of cycles)
- The SI unit of period is the second [s].
- Frequency (ƒ) is the number of cycles of a repeating sequence of events in a unit interval of time.
- ƒ = n/t (number of cycles per time)
- Frequency and period are reciprocals (or inverses) of one another: ƒ = 1/T.
- The SI unit of frequency is the hertz [Hz = 1/s = s−1].
- Wavelength (λ) is the distance between any point on a periodic wave and the next point corresponding to the same portion of the wave measured along the path of propagation.
- Wavelength is measured between adjacent points in phase.
- The SI unit of wavelength is the meter [m].
- Speed (v) is …
- Waves propagate with a finite speed (sometimes called the wave speed) that depends upon …
- the type of wave,
- the composition of the medium, and
- the state of the medium
- v = Δs/Δt the rate of change of distance with time by definition and
- v = ƒλ the product of frequency and wavelength for periodic waves.
- Frequency and wavelength are inversely proportional.
- Lower frequency waves have longer wavelengths.
- Higher frequency waves have shorter wavelengths.
- The speed of a wave is sometimes known as its wave speed
- The SI unit of speed is the meter per second [m/s].
- Waves propagate with a finite speed (sometimes called the wave speed) that depends upon …