Wave Characteristics Guided Notes
Name:__________________ Class:____
What is a wave?
Watch the two waves.
How do the particles move?
Key point: Waves carry ________________ not _____________.
Definition: A wave is a disturbance that _______________________________ through matter or space
____________________________________________________ .
The energy carried by a wave can be substantial – think of earthquakes, tsunamis, or the heat and light of the sun.
Transverse Waves
The particles of the medium oscillate __________________________to the direction of energy transfer/propagation of
the wave.
Examples:
• earthquake secondary waves,
• waves on a stringed musical instrument
• waves on the rope,
• EM waves: light, radio waves, microwaves…
Longitudinal Waves
The particles of the medium oscillate __________________________ to the direction of energy transfer/propagation of
the wave.
Creates areas of increased and decreased density
• Areas of high density / pressure = _____________________
• Areas of low density / pressure = _____________________
Examples
• Sound waves
• Earthquake p waves
• Compression in a spring
Wave Characteristics
Wavelength (λ)
 The ________________________________________________________ of a wave
 measured in meters
Phase
 Two points on a wave that occur in the same position within the wave cycle – that is, they are one or more
whole wavelengths apart -- are said to in phase.
 Points in a wave medium can be anywhere from 0° to 360° out of phase with each other.
 A trough and a crest are 180° out of phase with each other.
Amplitude, A
● the ______________________________________________________________________________________.
● measured in m
● the _________________________________________, the ____________________________________of the wave
● if a wave doesn’t lose energy, then its amplitude remains constant; if the wave does lose energy then the amplitude
decreases over time (damping)
Period, T
● is the _____________________________________________________________________________________.
● measured in seconds
Frequency, f
● is the _______________________________________________________________________________________.
● measured in cycles per seconds or Hz
f=
1
T
T=
1
f
Wave speed, v
● The _______________________________________________________________________________.
● ___________________________________________________________ through which a wave travels!
Waves travel faster through material that is stiffer and through material that is less dense.
Speed of sound in:
air: 343 m/s
helium: 1005 m/s
water: 1500 m/s
bone: 3000 m/s
steel rod: 5000 m/s
glass: 4500 m/s
Mechanical vs. EM waves
Mechanical Waves
● _________________________________________________________________________________
● Make the particles of the medium oscillate at frequency of the wave
Examples: waves on a string, sound waves, earthquakes, etc.,
EM (electromagnetic) waves
● __________________________________________________________________________________
● Do not cause the particles of the medium to oscillate
● Made up of changing electric and magnetic fields
● always occur as transverse waves
● In a vacuum, EM waves travel at the speed of light
c ≈ 3 x 108 m/s
(EM waves travel more slowly through a medium)
Wave Equation
A wave generator was used to generate waves of different frequencies in a rope. Two different tensions of rope where
used. The wave speed and wavelength were measured.
Use the data in the table to answer the following questions
a) Which variable(s) affected wave speed?
b) How are wavelength, frequency, and speed related?
Check Your Understanding
You Do
1.
A sound wave produced by a clock chime is heard 515 m away 1.5 s later.
(a) What is the speed of sound in the air there?
(b) The sound wave has a frequency of 436 Hz. What is the period of the wave?
(c) What is the wave's wavelength?
2.
A hiker shouts toward a vertical cliff 465 m away. The echo is heard 2.75 s later.
(a) What is the speed of sound in air there?
(b) The wavelength of the sound is 0.75 m. What is the frequency of the wave?
(c) What is its period?