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Altius Lesson: Physics 4

Terms in this set (76)

Wavelength Definition (wave)
The length of one complete wave cycle. Crest to Crest or Trough to Trough.
Period Definition (wave)
The time for a particle on a medium to make one complete vibrational cycle. Period, being a time, is measured in units of time such as seconds, hours, days or years.
Velocity Definition (wave)
In the case of a wave, the speed is the distance traveled by a given point on the wave (such as a crest) in a given interval of time.
Amplitude Definition (wave)
refers to the maximum amount of displacement of a particle on the medium from its rest position.
Frequency Definition (wave)
refers to how often the particles of the medium vibrate when a wave passes through the medium.
Intensity Definition (wave)
the average power transfer over one period of the wave is used. Power= Change in E / time
Phase Definition (wave)
the fraction of the wave cycle which has elapsed relative to the origin.
In order for two waves to have the same phase, what two things must be shared?
Wavelength, frequency, and period...NOT AMPLITUDE!
Intensity
Power per unit area. INTENSITY of any sound or mechanical wave is directly proportional to the amplitude squared and the frequency squared.
Units of Intensity
W/m2
Attenuation
The gradual loss of intensity as a wave passes through a medium. In non dispersive mediums this is due to scattering (reflection) of some waves and absorption of wave energy.
Attenuation formula
A=4pi r2
What is the decibel system?
A rating system for the intensity of sound within the range of human hearing. A 10-fold increase in sound intensity are represented by a 10 unit change on the decibel scale. A sound 100x's more intense is rated 20 decibels higher and 1000x's more intense is 30 decibels higher.
Intensity in decibels =
I is intensity of sound wave in W/m2
Io is the threshold of human hearing ( 1 e-12 W/m2; always given)
Transverse vs. longitudinal waves
Transverse waves displace the medium perpendicular to their direction of travel and longitudinal waves displace the medium parallel to their direction of travel (sound waves, p-wave earthquakes).
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