This document defines and classifies waves, describing mechanical and electromagnetic waves. It explains that mechanical waves require a medium and can be longitudinal or transverse. Longitudinal waves involve compression and rarefaction, while transverse waves involve up-and-down or side-to-side motion perpendicular to the propagation direction. The document also describes key characteristics of waves like wavelength, amplitude, frequency, period, and how to calculate wave speed using wavelength and frequency. An example is provided of students conducting a slinky experiment to study how variables affect wave speed.

2. What is a wave?
 A disturbance that moves through matter or space.
 Energy moving from place to place.
 The matter or space that the wave travels through is
called a medium

3. Classification of waves
 There are two main categories of waves:
1. Mechanical Waves (our focus now )
~ Require a medium in order to transport their energy
from one location to another.
~ Ex: Sound
2. Electromagnetic Waves (we will look at these in more
detail next week)
~ EM waves are capable of transmitting energy through a
vacuum (i.e., empty space).
~ Ex – Photons of light

4. Mechanical Waves
 Two types of waves:
1. Longitudinal (aka Compressional)
•Longitudinal waves look like a slinky
•Direction of medium is parallel to the direction of wave
propagation (motion)
•Ex: Sound Waves - move air back and forth

5. Characteristics of a Longitudinal Wave
2 areas
Compression- an
area of high
molecular density and
pressure
Rarefaction - an area
of low molecular
density and pressure

6. Mechanical Waves
 Two types of waves:
2. Transverse
•Transverse waves look like a sine curve
•Direction of medium is perpendicular to direction of wave
propagation (motion)
•Ex: Water Waves - move stick up and down in a pond

7. Characteristics of a Transverse Wave
1)Crest- highest position
Crest of the wave
2) Trough- lowest
position of the wave
3) Wavelength- the
distance between two
‘like’ points on a wave
(crest to crest; trough
to trough)
4) Amplitude- Height of
Trough
the wave (from origin
to crest or trough)
5) Frequency- The
number of crests that
pass by a point each
second.

8. Measuring a Wave
Frequency vs. Period
 Frequency is how many  Period is the number of
waves pass by you (or an seconds (usually it’s less than
arbitrary point) per 1 second) it takes for 1 WAVE
second, measured in to pass by you, measured in
Hertz. seconds or seconds per wave.
1 1
f T
T f

9. Measuring a Wave
 Wave motion compared to linear motion
 Wavelength is comparable to displacement
 Period is comparable to time
 To find linear speed you use the equation:
distance
speed
time
v f
 To find wave speed do the same thing, just with wave variables:
wavelength( )
wave speed (v)
period ( )
Since frequency is the inverse of period you will usually see the
equation : wave speed = wavelength x frequency
Units: Since a “cycle” is not a standard unit this gives you m/s.

10. Stan and Anna are conducting a slinky experiment. They are studying
the possible affect of several variables upon the speed of a wave in a
slinky. Their data table is shown below. Fill in the blanks in the table.
Medium Wavelength Frequency Speed
Zinc, (1.75)(2)= 3.5m/s
1.75 m 2.0 Hz ______
1-in. dia. coils
Zinc, (0.9)(3.9)= 3.51m/s
0.90 m 3.9 Hz ______
1-in. dia. coils
Copper, (1.19)(2.1)= 2.499m/s
1.19 m 2.1 Hz ______
1-in. dia. coils
Copper,
0.60 m 4.2 Hz (0.6)(4.2)= 2.52m/s
______
1-in. dia. coils
Zinc, (0.95)(2.2)= 2.09m/s
0.95 m 2.2 Hz ______
3-in. dia. coils
Zinc, (1.82)(1.2)= 2.18m/s
1.82 m 1.2 Hz ______
3-in. dia. coils