Forms of Energy
Description
A. Energy is involved in all physical processes and is a unifying concept
in many areas of science.
B. Energy exists in many forms and has the ability to do work or cause a
change.
Benchmark Number & Descriptor
 SC.7.P.10.1
 Illustrate that the sun's energy arrives as radiation with a
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wide range of wavelengths, including infrared, visible, and
ultraviolet, and that white light is made up of a spectrum of
many different colors.
SC.7.P.10.2
Observe and explain that light can be reflected, refracted,
and/or absorbed.
SC.7.P.10.3
Recognize that light waves, sound waves, and other waves
move at different speeds in different materials.
NATURE OF WAVES
 Waves (Def.) – A disturbance that
transfers energy
 Medium – Substance through which a
wave moves through
 Speed of Waves – Depends on the
properties of the medium
What are the parts of a wave?
Transverse wave
•The crest = highest point on a
transverse wave
•The trough = lowest point on
a transverse wave
•The wavelength is the
distance from one point on the
wave to the next corresponding
adjacent point
•EX: Trough to trough
Crest to crest
What are the parts of a wave?
Compressional (Longitudinal) Wave
•Compression = Tightly coiled section
•Refraction = Loose, less coiled section
•Wavelength = the distance from one point on
the wave to the next corresponding adjacent
point
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WAVELENGTH and FREQUENCY
 The distance from one point on
the wave to the next
corresponding adjacent point
 The smaller the wavelength, the
more times it will pass through a
point in one second
 The larger the wavelength, the
fewer times it will pass through a
point in one second
 Frequency is the number of
waves that pass through a
point in one second.
 The unit for frequency is
waves per second or Hertz
(Hz).
 One Hz = One wave per
second.
 Wavelength and frequency
are inversely related.
What is wavelength?
What is wave frequency?
What is the amplitude of a wave?
 Transverse Wave
 Height of crest trough
from standstill
 Larger the height,
greater the energy
 Compressional Wave
 Greater amplitude =
Tighter coils
 Less amplitude = Loose
coils
KNOWLEDGE CHECK
1.
How does the frequency of a wave relate to its
wavelength?
2. Name two types of waves.
3. Name two parts of each wave.
4. How is amplitude of a longitudinal wave measured?
KNOWLEDGE CHECK
1.
How does the frequency of a wave relate to its wavelength?
The greater the frequency, the smaller the wavelength.
2.
Name two types of waves? Longitudinal and Transverse
3.
Name two parts of each wave.
Longitudinal = Compression/Rarefaction
Transverse = Crest/trough
4.
How is amplitude of a longitudinal wave measured? Based on
the tightness of the coils
 We see things because they reflect
light into our eyes:
Homework
Electromagnetic Spectrum
Visible Spectrum – Light we can see
Roy G. Biv – Acronym for Red,
Orange, Yellow, Green, Blue, Indigo,
& Violet
Largest to Smallest Wavelength
Light
 Our primary source of light is the sun.
 Light travels in straight lines at a speed of 186,000
miles per second.
 Light waves travel faster than sound waves!
 Light energy from the sun travels through space,
reaches earth, and some of it turns to heat energy
and warms the earth’s air.
 Light from the sun also travels to the cells of
green plants (producers) and is stored as energy.
 When light reaches an object, it is absorbed,
reflected, or passes through it.
KNOWLEDGE CHECK
1.
What is the order of the Electromagnetic Spectrum?
2. What is our major source of light energy?
3. Which travels faster, light or sound?
KNOWLEDGE CHECK
What is the order of the Electromagnetic Spectrum?
ROY G. BIV (red, orange, yellow, green, blue, indigo,
violet)
2. What is our major source of light energy? The Sun
1.
3. Which travels faster, light or sound? Light waves
How Waves React
Reflection
 A bouncing back of a
wave after it hits a
barrier
 Does not go through a
barrier
 Echo = reflection of a
sound wave
Reflected ray
Incident ray
Mirror
REFRACTION
 Bend a wave at an angle
as it hits a
medium/barrier
 Light waves -> Prism ->
Rainbow
 Light (colors) have a
different wavelength; a
prism breaks them apart.
Transparent objects:
 ALL of these are
transparent.
 We can see through
them because light
passes through each of
them.
 The windows on a school
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bus
A clear empty glass
A clear window pane
The lenses of some
eyeglasses
Clear plastic wrap
The glass on a clock
A hand lens
Colored glass
Translucent objects
 All of these materials are
translucent .
 Thin tissue paper
 Waxed paper
 Tinted car windows
 Allow some light to pass
but the light cannot be
clearly seen through.
 Frosted glass
 Clouds
Opaque objects
 All of these objects are
 Heavy weight paper
opaque because light
cannot pass through
them at all.
 They cast a dark shadow.
 Cardboard
 Aluminum foil
 Mirror, bricks, buildings
 Your eyelids and hands
 Solid wood door
KNOWLEDGE CHECK
1.
Name a material that is opaque and reflects light
waves?
2. Name a material that is transparent and refracts the
light waves?
3. Name a material that is translucent and scatters
light waves?
KNOWLEDGE CHECK
1.
Name a material that is opaque and reflects light
waves? Mirror
2. Name a material that is transparent and refracts the
light waves? Water
3. Name a material that is translucent and scatters
light waves? Clouds
SOUND WAVES
SOUND WAVES
 We hear sound which
 The denser the medium,
 Sound can travel through
 The higher the
usually travels through air.
other mediums such as
water and various solids.
 Sound travels different
speeds through different
mediums.
 Sound generally travels
faster in a solid than a
liquid and faster in a liquid
than a gas.
the faster sound will travel.
temperature, the faster the
particles of the medium
will move and the faster
the particles will carry the
sound.
What is sound intensity?
 Sound intensity is the
energy that the sound
wave possesses.
 The greater the intensity
of sound the farther the
sound will travel and the
louder the sound will
appear.
 Loudness is very closely
related to intensity.
 Loudness is the human
perception of the sound
intensity.
 The unit for loudness is
decibels.
How is frequency related to pitch?
 The pitch of a sound wave
 A healthy human ear can
 A high-pitched sound has a
 Humans cannot hear
is directly related to
frequency.
high frequency.
 ex. screaming girl
 A low-pitched sound has a
low frequency.
 ex. fog-horn
hear frequencies in the
range of 20 Hz to 20,000
Hz.
below 20 Hz. Sounds
below this frequency are
termed infrasonic.
 Sounds above 20,000 Hz
are termed ultrasonic.
 Some animals, such as
dogs, can hear frequencies
in this range in which
humans cannot hear.
Loudness in Decibels
KNOWLEDGE CHECK
1.
What type of matter does sound travel best
through?
2.
How does temperature affect the speed of sound?
3. What is the relationship between pitch and
frequency?
KNOWLEDGE CHECK
What type of matter does sound travel best
through? Solids
2. How does temperature affect the speed of sound?
The higher the temperature, the faster the sound
will travel.
3. What is the relationship between pitch and
frequency? Pitch and frequency are directly related.
1.