Characteristics of Waves
Chapter 14.2
Wave Shape
• Waves take the form of sine curves
(from math!)
• Transverse wave:
Wave Terms!
• Crest  the highest point of a wave
• Trough  the lowest point of a wave
Wave Terms
• Amplitude the maximum distance
that the particles of a wave’s medium
vibrate from their rest position
• Wavelength (λ) the distance from any
point on a wave to an identical point on
the next wave
Wave Terms
• Period (T)  the time that it takes a complete
cycle or wave oscillation to occur
• Frequency (f)  the number of cycles or
vibrations per unit of time
Frequency (f)
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Frequency = 1 / Period
f=1/T
T=1/f
Frequency is measured in Hertz (Hz)
Period (T) is measured in seconds (s)
Wave Speed (v)
• Wave speed = wave length / period
• v=λ/T
• Units for wave speed = meters / second
• Wave speed = frequency x wavelength
• v=fxλ
Example
• The string of a piano that produces the
note middle C vibrates with a frequency
of 264 Hz. If the sound waves produced
by this string have a wavelength in air
of 1.30m, what is the speed of sound in
air?
v=fxλ
v = (264 Hz) x (1.30 m)
v = 343 m/s
Sound travels at varying
speeds in different mediums
• What do you think? Which is the fastest
medium? Gas? Liquid? Solid?
• Sound travels fastest through a solid,
then a liquid, then through gas
• Related to the particle spaces in each
medium
• Solids  more packed particles 
faster vibrations
Speed of Light!
• Abbreviated by “c”
• Speed of light = 3.00 x 10^8 m/s
(186,000 miles/second) **through empty
space
• Light travels slower when it passes
through air or water
Visible Light
• Our eyes can only detect frequencies
ranging from
4.3 x 10^14 Hz to 7.5 x 10^14 Hz
• The electromagnetic spectrum of
visible light:
Doppler Effect
• Doppler Effect  an observed change
in frequency of a wave when the source
or observer is moving
• Pitch is determined by frequency of
waves
Doppler Effect
• When the ambulance is moving
towards you  sound waves are
compressed  higher frequency 
higher pitch you hear