Science Spectrum Answer Key continued
Chapter 16 Sound and
Light
Review
1. Both infrasound and ultrasound are out-
SECTION 1 SOUND
1. Student should label an area with close-
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together air particles “Compression”
and an area with far-apart air particles
“Rarefaction.”
longitudinal
cold air
Rubber absorbs or reduces vibrations, so
sound waves do not travel through it well.
the energy in the waves
When the drum is hit gently, less energy is
transmitted to it. Therefore, it vibrates less,
and the amplitude of the resulting sound
waves is smaller. The smaller amplitude
produces a reduced intensity, or loudness.
10 times
about four times
Trombones generally play lower-pitched,
and therefore lower-frequency, sounds than
trumpets.
the dolphin
standing waves
the frequency of the main standing wave on
a vibrating string
the top
the frequencies at which an object is most
likely to vibrate
More air molecules are in contact with the
guitar body.
through the outer ear
outer ear, middle ear, inner ear
a long, flexible membrane in the cochlea
They do not harm living cells.
no
The images are produced using ultrasound
waves.
a tool that uses reflected sound waves to
measure distances
Student should circle the highest point on
the ocean floor.
4.
5.
side the range of normal human hearing.
Infrasound has lower frequencies than
humans can hear. Ultrasound has higher
frequencies than humans can hear.
amplitude and distance from source
The first sound has a lower frequency and
smaller amplitude than the second sound.
left to right: outer ear; eardrum; middle ear;
cochlea
Both involve using sound waves to measure
or make images. Sonograms are images of
the human body. Sonar is used to produce
images of the ocean floor or other objects.
SECTION 2 THE NATURE OF LIGHT
1. They diffract.
2. transverse waves
3. Any three of the following: reflection,
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refraction, diffraction, interference
the bright red light
Possible answer: particles, photons
The bright red beam contains more photons
because it is brighter. Brighter lights contain more photons.
top row: wave model
second row: particle model
third row: wave model
bottom row: particle model
photons
ultraviolet
air
The light spreads out as it travels.
Student should circle the largest area.
gamma rays
radio waves
a system that uses radio waves to locate
objects
centimeters
a phone signal
temperature changes and cloud movements
in the atmosphere
more
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Interactive Reader
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Answer Key
Science Spectrum Answer Key continued
Review
1. Possible answers: police use radar to track the
2.
3.
4.
5.
6.
11. white
12. It absorbs all colors of visible light.
speed of vehicles; air-traffic control uses radar
to track location and elevation of aircraft.
Neither model can completely explain all the
observations about the behavior of light.
Observations that support the wave model
include the fact that light shows reflection,
refraction, diffraction, and interference.
Observations that support the particle
model include the fact that light can travel
through a vacuum and that light can cause
electrons to fly off pieces of metal.
The energy of photons of light is proportional to the frequency of the electromagnetic waves. Therefore, photons associated
with visible light have more energy than
photons associated with radio waves,
because visible light has higher frequencies
than radio waves.
UV light has high enough energy that it can
pass through clouds. It can give you a sunburn. Sunscreen protects skin by absorbing or blocking ultraviolet light before it
reaches your skin.
gamma rays, X rays, ultraviolet rays,
visible light, infrared light, microwaves,
radio waves
Review
1. to make it easier to understand and predict
2.
3.
4.
5.
SECTION 4 REFRACTION, LENSES, AND
PRISMS
1.
2.
3.
4.
SECTION 3 REFLECTION AND COLOR
1. an imaginary line that shows the direction in
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how light waves will behave during reflection
and refraction
Answers will vary. Students should give
examples of objects that are dull or matte
in appearance. Objects that produce diffuse
reflection look dull.
Student should label the vertical line
“Normal,” the angle between the downward-pointing line and the normal “Angle
of incidence,” and the angle between the
upward-pointing ray and the normal “Angle
of reflection.”
Possible answers: 25°, or the same as the
angle of incidence
A blue object reflects blue light. If you shine
red light on it, there is no blue light for it to
reflect, so it appears black.
which light travels
dull
The angle of incidence of a light ray is equal
to the angle of reflection.
Student should draw an incoming ray that
makes a smaller angle with the normal, and
a reflected ray that makes the same angle
with the normal, but is on the other side of
the normal.
a virtual image
His brain interprets the reflected light waves
as if they traveled in a straight line from
behind the mirror.
They distort reflected images.
Light rays pass through a real image, but
they do not pass through a virtual image.
the relative positions of the object and the
mirror
the wavelengths of light it reflects
5.
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Its speed changes.
It decreases.
air
Light reflecting from below the water
refracts as it moves from the water to the
air, producing a virtual image that your eye
detects.
Student should circle the point at which all
of the light rays converge.
virtual
Muscles around the lens change its shape to
change the amount that light is refracted.
violet
violet
the separation of light into different colors
because of differences in wave speed
dispersion and reflection
Review
1. Dispersion occurs because different wave-
lengths of light refract by different amounts
when they pass through a prism.
2. In order of flow chart: cornea; lens; lens;
retina; rods; cones; optic nerve
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Answer Key
Science Spectrum Answer Key continued
Review
1. In electrical conductors, electrons can
3. Possible answers: magnifying glass, human
eye, microscope
4. Rainbows form because of a combination
of dispersion and reflection. Dispersion
happens because different wavelengths of
light travel at different speeds in a medium.
If all wavelengths of light traveled at the
same speed in a given medium, no dispersion
would occur, and rainbows would not form.
5. converging
6. green light
2.
Chapter 17 Electricity
3.
SECTION 1 ELECTRIC CHARGE AND
FORCE
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The particle has a positive charge.
electrons
They have opposite electric charges.
negative
1.6 1019 C
Electrons are located in the outer parts of
an atom.
The toaster would not work if the cord were
made entirely of plastic. Plastic is an insulator,
so electricity does not flow through it easily.
It contains the same number of protons as
electrons.
It has a negative charge, so it must have
more electrons than protons.
friction
Electrons cannot move easily through an
insulator.
positive
a force a charged object experiences due to
interactions with other charged objects
amount of charge on each object and distance between the objects
away from each other
a force that can affect objects that are not
touching
because a positively charged object will
repel another positively charged object
Electric field lines show how a positively
charged particle would move. A positively
charged particle would be repelled by
the positively charged particles in the left
image.
4.
5.
move freely throughout the substance.
Therefore, electrical conductors can
transfer electric charge easily. In electrical
insulators, electrons cannot move freely.
Therefore, electrical insulators do not
transfer electric charge easily.
There is more friction between your feet
and a carpeted floor than between your
feet and a smooth floor. The greater friction
causes more electrons to move between the
floor and your body.
More electrons will move into student A’s body
than into student B’s body. Therefore, the
difference in electric charge between student
A and the doorknob will be greater. Student A
is more likely to receive an electric shock.
The greater the charges, the greater the
electric force.
toward the object
SECTION 2 CURRENT
1. energy that charged objects have that
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depends on their position in an electric field
It decreases.
It would decrease.
voltage
12 V
from areas of high potential to areas of low
potential
electrons
from right to left
the slowing of the movement of charged
particles through a substance
resistance
They travel through the wires in the bulb.
by dividing voltage by current
V IR;
V (0.50 A) × (12 7); V 6 V
Electrons can move through them easily.
Metal is a better electrical conductor than
plastic, so the metal fork probably has
lower resistance than the plastic fork.
to allow electricity to flow through the device
a material that has no resistance below a
certain temperature
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Answer Key