Transcript What is a wave?

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Characteristics of Waves Notes
11/15
Answer:
Essential Questions:
1)
1) Compare
and Contrast a
mechanical wave with an
electromagnetic wave.
2)
2) What
type of wave is a
sound wave?
3)
3) Explain
Key Words/Question

how energy is
transferred by a wave.
Key Words: wave, medium, mechanical waves,
energy, transverse wave, compressional/longitudinal
wave, electromagnetic wave
What is a wave?

Webster's dictionary defines a wave as "a
disturbance or variation that transfers
energy progressively from point to point in
a medium and that may take the form of
an elastic deformation or of a variation of
pressure, electric or magnetic intensity,
electric potential, or temperature."
Waves
Animation
Wave – a repeating movement or disturbance that
transfers energy through a matter or space.
All waves carry energy without transporting matter
from place to place

Molecules pass energy along to neighbor molecules
who then pass energy to neighbor

All waves are produced by vibrations

Waves will travel as long as there is energy to carry.

The medium a wave travels through may experience
some vibrations as the wave passes, but the particles
in the medium do not travel with the wave.
Motion of Particles in a Wave
Waves move
energy
Not matter
Medium - The type of matter (environment) that the
wave travels through.

A medium can be solid, liquid, gas or a combo of
these


Examples: air, water, earth, rope.
Not all waves need a medium to travel – light and
other Electromagnetic waves can travel without a
medium (in space, or a vacuum).
Mechanical Waves – waves that can only travel
through a medium.
Compressional/Longitudinal
Waves:
Transverse Waves:
Matter moves back and forth Matter in medium moves in the
at right angles to the direction same direction that wave
travels.
that the wave is moving.
Electromagnetic Waves – Made by vibrating the
electrical charges and can travel through empty
space without a medium.
Transverse Waves
Compressional/
Longitudinal Waves
Compressional Wave (longitudinal wave)
OCEAN WAVES
Direction of wave movement
A Combination of Longitudinal and Traverse Waves
Direction of wave movement
Review Questions





Define: Wave, medium, mechanical wave,
electromagnetic wave
What direction does a wave travel to the medium in a
compressional wave?
What is an example of a transverse wave?
What is unique about ocean waves versus sound waves?
What is the difference between a mechanical wave and an
electromagnetic wave?
Summary Activity:
1) Answer Essential Questions, use details from notes
and discussion for full credit.
2) Complete concept map and GLUE into ISN.
Features/Characteristics
of Waves
Features/Characteristics of Waves Notes
Answer:
Essential Questions:
1)
1) Describe
and distinguish
between the following
characteristics of a wave:
wavelength, frequency,
amplitude, period.
Key Words/Question

Key Words: compression, rarefaction, crest, trough,
amplitude, wavelength, rest position, frequency,
period, inverse relationship
Parts of a Wave
Transverse waves have crests – the highest points from the resting
position, and troughs – the lowest points from the resting position.
Compressional waves have dense regions (coils close together) called
compression, and less dense regions called rarefactions.
Amplitude – a measure of energy in a wave, the more energy a wave
carries = greater amplitude.
 Distance from crest or trough to normal position (resting position)
in a transverse wave.
 The denser the compression, the larger the amplitude in a
compressional wave.
Amplitude
Wavelength (λ) – distance between one point on a wave and a
similar point nearest to it (crest to crest, trough to trough,
compression to compression, or rarefaction to rarefaction)
Frequency – number of wavelengths that pass a fixed point each
second (hertz = Hz)
Inverse relationship between period (time) and frequency. When you
increase one, the other decreases.
If you increase the number of waves in 1 second, your frequency will increase, and if you
increase the amount of time it takes for 1 wave cycle, you decrease your frequency.
A
B
C
Frequency
1 cycle of a wave = distance from resting
point – crest – trough – resting point.
1 Hz = 1 cycle per second
A)1 cycle/second = 1
Hz
B)2 cycle/second = 2
Hz
C)4 cycle/second = 4
Hz
D)8 cycle/2 second= ?
Review Questions
•
How do you determine the wavelength in a compressional /
longitudinal wave and a transverse wave?
•
What is the symbol for wavelength?
•
What happens to a waves amplitude when the energy carried
increases?
•
What is the symbol for amplitude?
•
How do you determine the amplitude in a compressional /
longitudinal wave and a transverse wave?
•
Define the frequency of a wave?
•
What is the formula for determining frequency? What is the symbol?
•
Define period?
•
Describe the relationship between frequency and period?
Summary Activity

Answer the Essential Questions. For full credit,
use your notes and vocabulary to explain your
answer.

Complete the graphic organizer, diagraming a
transverse wave and a
compressional/longitudinal wave. GLUE into
your ISN
Wave Speed
Features/Characteristics of Waves Notes
Answer:
Essential Questions:
1)
1) Contrast
the difference between
an inverse and direct relationship
in formulas.
2)
3)
2) Describe
the relationship between
velocity, frequency, and
wavelength.
Key Words/Question

3) Which
medium does sound travel
fastest in: a solid, liquid, or gas
Key Words: direct relationship, wave speed, bar
graph, line graph, constant
Relationship between frequency and wavelength - If you increase the
wavelength of a wave, you decrease the frequency. If you decrease the
wavelength of a wave, you decrease the frequency.
λ=
f
λ=
Wave Speed – how fast a wave travels
through a given medium.
Speed through a given type of medium is
constant (does not change).
• Waves will travel through fresh water
at a constant speed, oil at a different
speed, sand at another, etc…
• Traveling from one type of medium to
another will change the speed of the
wave.
f
Using a Bar Graph, graph the speed of sound in each type of medium.
Using a line graph, graph the speed of sound as it travels through 5
different mediums. (for extra credit create a story that goes along with
the graph).
Calculating Wave Speed
Wave speed (m/s) = frequency (Hz) x wavelength (m)
V=fλ
Review Questions
Summary Activity

Answer the Essential Questions. For full credit,
use your notes and vocabulary to explain your
answer.

Complete the wave speed practice problems.
GLUE them into your ISN
Watch the following movie
clip. . .
Could you hear the explosion if
you were in space? Why or why
not?
Check your Understanding
√

Complete Note summary for Characteristics of Waves- will be checked
with notes!

Vocabulary Cards Due FRIDAY: Wave, longitudinal wave, compression,
rarefaction, transverse wave, crest, trough, wavelength, amplitude,
frequency, hertz, oscillation

Current Event # 5 due Monday/Tuesday next week. New Rubric!!!

Quiz on Wave Characteristics on Monday/Tuesday