Waves transport energy through a medium and do not transport matter. They are caused by vibrations or oscillations within a medium. There are two main types of waves - transverse waves, where the medium moves perpendicular to the direction of energy transport, and longitudinal waves, where the medium moves parallel to the direction of energy transport. The key characteristics of waves include their amplitude, wavelength, frequency, and period. Frequency refers to the number of oscillations per second, while period is the time for one full oscillation. Mechanical waves require a physical medium to travel through and include water waves and sound waves.

2. NATURE OF WAVE

3. WHAT IS A WAVE?
•Waves are an energy
transport phenomenon, a
way to transport energy
from one location to
another.

4. WHAT MAKES A WAVE A WAVE?
•Waves are caused by
vibrations
•A vibration (or oscillation)
is a back-and-forth or up-
and-down motion; a
wiggle in time.

5. •A wave does NOT
carry matter with it!
It just moves the
matter as it goes
through it.

6. WHAT IS A MEDIUM?
•A medium is a
substance or material
that carries the wave.
••
•The wave medium is not the
wave and it doesn't make
the wave; it merely carries or
transports the wave from its
source to other locations.

7. TRUE or FALSE:
In order for John to hear Jill, air molecules must move from the lips of Jill to the ears of John.
TRUE or FALSE:
In order for John to hear Jill, air
molecules must move from the
lips of Jill to the ears of John.
CHECK YOUR UNDERSTANDING

8. ANSWER
•False.
•A sound wave involves the movement of
energy from one location to another, not
the movement of material. The air
molecules are the particles of the medium,
and they are only temporarily displaced,
always returning to their original position.

9. CHECK YOUR UNDERSTANDING
•Mac and Tosh are experimenting with pulses on
a rope. They vibrate an end up and down to
create the pulse and observe it moving from
end to end. How does the position of a point on
the rope, before the pulse comes, compare to
the position after the pulse has passed?

10. ANSWER
•The point returns to its original
position. Waves (and pulses) do not
permanently displace particles from
their rest position.

11. CHECK YOUR UNDERSTANDING
A medium is able to transport a wave from one
location to another because the particles of the
medium are ____.
a. frictionless
b. isolated from one another
c. able to interact
d. very light

12. ANSWER
•Answer: C
•For a wave to be transmitted through a
medium, the individual particles of the medium
must be able to interact so that they can exert a
push and/or pull on each other; this is the
mechanism by which disturbances are
transmitted through a medium.

13. CHECK YOUR UNDERSTANDING
• Minute after minute, hour after hour, day
after day, ocean waves continue to splash
onto the shore. Explain why the beach is
not completely submerged and why the
middle of the ocean has not yet been
depleted of its water supply.

14. •Ocean waves do not transport water. An
ocean wave could not bring a single drop
of water from the middle of the ocean to
shore. Ocean waves can only bring energy
to the shore; the particles of the medium
(water) simply oscillate about their fixed
position. As such, water does not pile up on
the beach.
ANSWER

15. CATEGORIES OF WAVES
•MECHANICAL WAVE--
is a wave that is an
oscillation of matter,
and therefore transfers
energy through a
medium
• Some of the most common examples of mechanical waves are
water waves, sound waves, and seismic waves.

16. ELECTROMAGNETIC WAVES
• – DO NOT NEED matter (or medium) to
transfer energy
• They do not need a medium, but they can go
through matter (medium), such as air, water,
and glass.
• EXAMPLES are: Radio waves, Light waves, thermal
radiation, X ray, visible light, microwave, infrared,
gamma rays etc. are the example of electromagnetic
waves. These waves together form the
electromagnetic spectrum.

18. CATEGORIES OF A WAVES
•Transverse waves:
Waves in which the
medium moves at right
angles to the direction
of the wave.
Transverse waves are
always characterized by
particle motion being
perpendicular to wave
motion.

20. PARTS OF TRANSVERSE WAVES:
Crest: the highest
point of the wave
Trough: the lowest
point of the wave

21. PARTS OF TRANSVERSE WAVES:
•The wavelength is
the horizontal
distance, either
between the crests
or troughs of two
consecutive waves.

22. PARTS OF TRANSVERSE WAVES:
•The amplitude is the
peak (greatest)
value (either positive
or negative) of a
wave. The distance
from the undisturbed
level to the trough
or crest.

23. AN OCEAN WAVE IS AN EXAMPLE OF A
MECHANICAL TRANSVERSE WAVE

24. COMPRESSIONAL (OR LONGITUDINAL)
WAVES:
•Waves in which the
medium moves
back and forth in
the same direction
as the wave.

25. PARTS OF LONGITUDINAL WAVES:
Compression: where the
particles are close together
Rarefaction: where the
particles are spread apart

27. PARTS OF LONGITUDINAL WAVES:
The wavelength is the
distance from compression
to compression or
rarefaction to rarefaction
in a compressional wave.

28. A transverse wave is transporting energy
from east to west. The particles of the
medium will move_____.
a. east to west only
b. both eastward and westward
c. north to south only
d. both northward and southward
CHECK YOUR UNDERSTANDING

29. ANSWER
•Answer: D
•The particles would be moving back and forth
in a direction perpendicular to energy
transport. The waves are moving westward, so
the particles move northward and southward.

30. •A wave is transporting energy from left to
right. The particles of the medium are moving
back and forth in a leftward and rightward
direction. This type of wave is known as a ____.
a. mechanical b. electromagnetic
c. transverse d. longitudinal
CHECK YOUR UNDERSTANDING

31. •Answer: D
•The particles are moving parallel to the
direction that the wave is moving. This must be
a longitudinal wave.

32. A sound wave is a mechanical wave, not an
electromagnetic wave. This means
that______.
a. particles of the medium move perpendicular to the direction of
energy transport.
b. a sound wave transports its energy through a vacuum.
c. particles of the medium regularly and repeatedly oscillate
about their rest position.
d. a medium is required in order for sound waves to transport
energy.

33. •Answer: D
•Mechanical waves require a medium in order
to transport energy. Sound, like any
mechanical wave, cannot travel through a
vacuum.

34. Which of the following is not a
characteristic of mechanical waves?
a. They consist of disturbances or oscillations of a medium.
b. They transport energy.
c. They travel in a direction that is at right angles to the
direction of the particles of the medium.
d. They are created by a vibrating source.

35. •Answer: C
•The characteristic described in statement c is a
property of all transverse waves, but not
necessarily of all mechanical waves. A
mechanical wave can also be longitudinal.

36. •8. The sonar device on a fishing boat uses
underwater sound to locate fish. Would you
expect sonar to be a longitudinal or a
transverse wave?

37. •Answer: Longitudinal
•Only longitudinal waves are capable of
traveling through fluids such as water.
When a transverse wave tries to propagate
through water, the particles of the medium
slip past each other and so prevent the
movement of the wave.

38. WATER WAVES

39. RAYLEIGH SURFACE WAVES

40. ANATOMY OF A WAVE

42. •The crest of a wave is the point on the medium
that exhibits the maximum amount of positive
or upward displacement from the rest position.
•The trough of a wave is the point on the
medium that exhibits the maximum amount of
negative or downward displacement from the
rest position.

43. •The amplitude of a wave refers to the maximum
amount of displacement of a particle on the
medium from its rest position.
•The wavelength of a wave is simply the length of
one complete wave cycle. If you were to trace
your finger across the wave in the diagram above,
you would notice that your finger repeats its
path.

44. Consider the diagram below in order to answer questions #1-2.

45. a. A to C
b. B to D
c. A to G
d. C to G
Indicate the interval that represents one
full wavelength.

46. FREQUENCY AND PERIODS
•The frequency of a wave refers to how often
the particles of the medium vibrate when a
wave passes through the medium.
• UNIT: Hertz (abbreviated Hz)
• where 1 Hz is equivalent to
• 1 cycle/second.

47. •If a coil of slinky makes 2 vibrational cycles in
one second, then the frequency is 2 Hz. If a coil
of slinky makes 3 vibrational cycles in one
second, then the frequency is 3 Hz. And if a coil
makes 8 vibrational cycles in 4 seconds, then
the frequency is 2 Hz (8 cycles/4 s = 2 cycles/s).

48. PERIOD
•Period refers to the time that it takes to do
something.
•Period, being a time, is measured in units of
time such as seconds, hours, days or years.

49. DIFFERENCE BETWEEN FREQUENCY AND PERIOD
PERIOD
• Period refers to the time it
takes something to happen.
• Period is a time quantity.
• Period is the seconds/cycle.
•FREQUENCY
• Frequency is a rate
quantity.
• Frequency refers to how
often something happens.
• Frequency is the
cycles/second.

51. •A wave is introduced into a thin wire held tight
at each end. It has an amplitude of 3.8 cm, a
frequency of 51.2 Hz and a distance from a
crest to the neighboring trough of 12.8 cm.
Determine the period of such a wave.

52. • Answer: 0.0195 sec
• Here is an example of a problem with a lot of extraneous
information. The period is simply the reciprocal of the
frequency. In this case, the period is 1/(51.2 Hz) which is
0.0195 seconds.
• Know your physics concepts to weed through the extra
information.

53. •Frieda the fly flaps its wings back and forth 121
times each second. The period of the wing
flapping is ____ sec.

54. Answer: 0.00826 seconds
The quantity 121 times/second is the
frequency. The period is the reciprocal of
the frequency.
T=1/(121 Hz) = 0.00826 s

55. a. 5.0 b. 0.20 c. 0.12 d. 0.083
A tennis coach paces back and forth
along the sideline 10 times in 2 minutes.
The frequency of her pacing is ________
Hz.

56. •Answer: D
•Frequency refers to the number of occurrences of
a periodic event per time and is measured in
cycles/second. In this case, there are 10 cycles per
2 minutes (also known as 10 cycles per 120
seconds). So the frequency is
•f =10 cycles / 120 s = 0.0833 cycles/s

57. REFERENCES
• http://www.acs.psu.edu/drussell/Demos/waves/wavemotion.html
• http://physics.tutorvista.com/waves/types-of-waves.html
• http://oceanservice.noaa.gov/education/yos/resource/JetStream/ocean/wave_max.h
tm
• http://www.physicsclassroom.com/class/waves/Lesson-2/The-Anatomy-of-a-Wave
• http://www.physicsclassroom.com/class/waves/Lesson-2/Frequency-and-Period-of-
a-Wave
• http://www.physicsclassroom.com/class/waves/Lesson-2/Energy-Transport-and-the-
Amplitude-of-a-Wave