Waves Sound and Light

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```					Waves, Sound, and Light

Chapter 3
Bell Work 11/29/10
Please get a new bell work sheet. Write
each statement then decide if they are
true or false, if false correct them.
1. Mechanical waves transfer energy
through a vacuum.
2. A wave is a disturbance that transfers
energy.
3. An example of a longitudinal wave is a
water wave.
Light 3.1 Vocab
Electromagnetic wave – a disturbance that
transfers energy through a field

Radiation – energy that moves in the form
of EM waves
How EM waves form and sources
of EM waves
• Electric and magnetic fields make up EM
waves
• Many of the EM waves on Earth’s
environment come from the Sun.
• Stars give off EM waves but since they are
so far away not many of their waves hit the
Earth
• Technology is also a source of EM waves
Bell Work 11/30/10
1. What are the two types of
fields that make up an EM
wave?
2. How are EM waves used to
measure distances in space?
3. How does microwave cooking
depend on reflection?
Electromagnetic spectrum
• The range of all EM frequencies
• The spectrum goes from the lowest
frequencies to the highest
frequencies
• Higher-frequency EM waves with
more electromagnetic vibrations per
second have more energy than lower-
frequency EM waves
Measuring EM Waves

• EM wave frequency is
measured in hertz (Hz)
• One hertz equals one cycle
per second
• Have the longest wavelengths, the lowest
frequencies, and the lowest energies

Microwaves
• EM waves with shorter wavelengths, higher
frequencies, and higher energy than other
control air traffic at airports, analyze weather
conditions and measure the speed of a
moving vehicle
• Radar led to the invention of microwave
ovens
that uses microwaves
Bell work 11/25/09
1. List the colors of the visible light
spectrum in order from longest
wavelength to shortest wavelength.

2. What are the 7 parts of the
electromagnetic spectrum?
Bell Work 11/30/09

1. Give an example of using a radio wave.

2. Give an example of using a microwave.

3. Give an example of using an x-ray.
Bell Work 12/1/09
1. What do electromagnetic waves
transfer energy through?

3. How does a microwave cook
food?
Visible Light
• The part of the EM spectrum that human
eyes can see.
• Longest wavelengths are red all the way to
violet
• ROY G BIV
• Red, Orange, Yellow, Green, Blue, Indigo,
Violet
Bell Work 12/2/09
1. What are EM waves measured in?

2. Give two examples of using a radio wave.

3. Give 3 examples of using a microwave.

4. List the colors of visible light from longest
wavelength to shortest wavelength.
Infrared Light
• Type of EM wave most often associated
with heat
• Sometimes referred to as heat rays
• You can feel it as warmth coming from the
sun, a fire, or a radiator
• Infrared lamps are used to provide warmth
in bathrooms and to keep food warm after
its been cooked
• Some animals can see in infrared light
Ultraviolet Light
• Has more energy than visible light
• The waves in this range can damage your skin and
eyes
• Sun block and UV-protection sunglasses are
designed to filter out the higher frequencies
• UV light can be used to sterilize medical instruments
and food by killing harmful bacteria
• IV light causes skin cells to produce vitamin D which
is essential to good health
• UV light is visible to some animals. Bees and some
other insects
X-rays
• Has a very high frequency and energy
• Pass easily through soft tissues of the
body, but are absorbed by the bone
• The x-rays pass through exposing the film
where there is no bone
• When getting x-rays other parts of the
body are covered with a lead vest to block
the x-rays
Gamma rays
• Highest frequencies and energies of any
EM waves
• Produced by some radioactive substances
as well as the sun and other stars
• Gamma rays can penetrate the soft and the
hard tissues of the body, killing normal cells
and causing cancer cells to develop
• Gamma rays can also be used to kill
cancer cells and fight tumors
Bell Work 12/3/09
1. Which group from the EM spectrum has
the highest frequencies?
2. Which group pass easily through soft
tissues of the body, but are absorbed
by the bone?
3. What can you use to filter out the high
frequencies of UV rays?
4. Which EM wave is most associated with
heat?
Bell Work 12/4/09

Predict what would happen if
you kept a green plant in the
dark for one month. Explain
why. (at least 3 sentences)
Vocab 3.3
Incandescence – the production of
light by materials at high
temperatures

Luminescence – the production of
light without the high temperature.
Many organisms produce their own
visible light through this.
Bioluminescence – production of
light by living organism. These
organism produce light from
chemical reactions rather than
intense heat.

Fluorescence – occurs when a
one wavelength and gives off EM
Bell Work 12/5/09
1. What happens to the speed of EM waves
in a vacuum?

2. What happens when microwaves
encounter water?

3. What produces the most EM waves on
Earth?
Light 3.4 Notes
Transmission – the passage of an
EM wave through a medium.

• If the light reflected from objects
did not pass through the air,
windows, or most of the eye, we
could not see the objects
Absorption – the
disappearance of an EM
wave into the medium

• Absorption affects how things
look, because it limits the light
available to be reflected or
transmitted
How Materials Transmit Light
• Transparent materials allow most of
the light that strikes them to pass
through.
• Translucent materials transmit some
light, but they also cause it to spread
out in all directions.
• Opaque materials do not allow any
light to pass through them, because
they reflect light, absorb light, or both
Scattering – the spreading out of light rays
in all directions, because particles reflect
and absorb the light

• Fog or dust in the air, mud in water, and
scratches or smudges on glass can all
cause scattering

• Scattering creates a glare and makes it
hard to see even through a transparent
material
Polarization – a quality of light in which
all of its waves vibrate in the same
direction
• Polarizing filters reduce glare and make
it easier to see objects

Prism – a tool that uses refraction to
that make up white light
• Prisms split light into colors by refracting
wavelengths in different amounts
Color Reflection and Absorption
The color of an object or material is
determined by two factors

1. the wavelengths it absorbs and
those it reflects

2. The wavelengths present in the light
that shines on the object
• A material that reflects all wavelengths
of visible light appears white

• A material that absorbs all
wavelengths of visible like appears
black

• A green lime absorbs most
wavelengths but reflects green, so the
lime looks green
Primary Colors of Light
• The human eye can detect only 3
color bands: red, green, and blue
• Your brain perceives these three
colors and various mixtures of them
as all the colors
Primary colors – red, green, and blue
– can be mixed to produce all the
possible colors
Primary Pigments
• Materials can be mixed to produce
colors just as light can

• Materials that are used to produce
colors are called pigments

Primary pigments – cyan, yellow, and
magenta
Bell Work 12/8/09
1. What color is something that absorbs all
the colors?
2. What color is something that reflects all
colors?
3. If an object absorbs most wavelengths
but reflects violet what color will it be?
Bell Work 12/9/09 – (fill in the blanks)
1. Bioluminescent animals produce light
through _________.
2. When light is absorbed into a medium, the
waves ________ in the medium.
3. The primary pigments create colors through
_____________ mixing.
4. An electromagnetic wave transfers energy
through a ______.
5. Most of the visible EM waves on Earth
come from the ______.

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