8th Grade Science 09/24/2014

Essential Question - How does a wave transfer
energy?

Objectives - I can...
 Describe
the relationship between the
frequency and wavelength of a wave
 Explain
why waves travel at different speeds.

Bell Ringer - Copy and answer the following
question on your bell ringer sheet.

How are mechanical waves and
electromagnetic waves different? How are they
alike?
Frequency,
Amplitude, and
Wavelength
8TH GRADE SCIENCE
Waves Review
A
wave is a traveling disturbance that
carries energy from one place to
another.
 Energy is the ability to do work or
cause a change
Amplitude
 Amplitude
- is
measured from the
equilibrium position
to the top of a crest
or the bottom of a
trough.
 The amplitude of a
transverse wave is a
measure of how
high the crests are or
how deep the
troughs are.
Wavelength

Another way to describe a wave
is by its wavelength.

The highest points of waves are
called crests.

The lowest points of waves are
called troughs.

A wavelength, for a transverse
wave, is the distance from one
crest to the next.

A wavelength, for a
compressional wave, is the
distance between the center of
one compression and the center
of the next compression.
The Electromagnetic Spectrum:
Wavelength
Visible light is only a small
part of the
electromagnetic
spectrum.
 It is the wavelength of
visible light waves that
determines their color.
 For example –
 The wavelength of red
light waves is longer
than the wavelength of
green light waves.

Frequency

Frequency is number of
complete wavelengths in a
given point.

As a wave length
increases in size, its
frequency and energy
decrease.
th
8
Grade Science 09/24/2014
Essential Question - How does a wave transfer
energy?
 Objectives - I can...
 Describe the relationship between the
frequency and wavelength of a wave
 Explain why waves travel at different speeds.
 Bell Ringer - Copy and answer the following
question on your bell ringer sheet.

 How
does increasing energy affect the
frequency and wave length of a wave?
(hint – Think about the turtle and Rabbit picture)
Frequency and Energy

As a wave length
increases in size, its
frequency and energy
decrease.

As a wavelength
decreases in size, its
frequency and energy
increase.
Agenda
Review wavelength, amplitude,
and frequency.
2. Notes on speed of waves
3. Begin Wave worksheet
4. Correct quizzes and complete
reflection sheet
1.
Review

Amplitude – the
measurement from the top
of the crest, or bottom of the
trough, to the middle
(equilibrium)

Wavelength – The length of a
single wave cycle

Frequency – the number of
waves that pass a given
point in a given amount of
time.
Speed of Waves

To calculate the speed of the wave, use the
formula:
Wave speed = Wavelength X frequency
10 cm
10 cm
Calculate the speed of the wave
5 cm
a. Wavelength _______ b. Amplitude _________ c. Frequency _______ d. Speed_________