Transcript Final Exam Review- New things you NEED to know

Electromagnetic Waves in a
Nutshell
Electromagnetic Waves Unit
• Waves are very important because
they transfer energy.
• Electromagnetic Spectrum is the
scientific name for radiation.
• Radiation is energy emitted from
waves (light) or from photons
(particles)
• Radio waves- Are used to give you tunes in
your car. Our the longest and weakest wave
length. Are also released by stars or gases in
the universe…They help scientists discover
what the stars are made of!
• Microwaves- much smaller in length (3 mm) is
also invisible. Allows you to pop popcorn but
also used to study the universe and
communicate with satellites that orbit earth.
• Infrared- thought of as “heat” but much of the
heat rarely reaches earth. Help astronomers
figure out the dust (gases) between stars.
• Visible- Things we can see such as light bulbs
and fireflies…ranging from red (longest wave
light of visible to violet- shortest wave length of
visible)
• Ultraviolet- Our atmosphere blocks most of this
but this is what causes your skin to burn. Stars
and other hot objects in space have UV rays.
• X-ray- Your doctor uses them to look at your
bones but hot gases in the universe also emit xrays.
• Gamma Rays- Radioactive materials some
natural some man-made cause gamma rays. The
biggest producer of gamma rays is the universe.
• Crest- The sections that rise above
the undisturbed line
• Trough- The sections that lie below
the undisturbed line.
• Amplitude- Is the positive or
negative displacement from the
normal line.
• Wavelengths- The wavelength of a wave is
the distance between any two adjacent
corresponding locations on the wave
train. This distance is usually measured in
one of three ways:crest to crest, trough to
trough or from the start of one wave cycle
to the next.
Reflection and Refraction
• Refraction- is when
waves are deflected
when the waves go
through a substance.
The wave generally
changes the angle of
its general direction.
• Reflection- Is when
waves bounce from a
surface back toward
the source. A mirror
reflects the image of
the observer.
1. Visible light can have different
colors because it can have
different:
Frequencies
Wavelengths
Energies
All of the above
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B.
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2. Of the waves listed, which one
has the longest wavelength?
Microwave
Radio waves
X-rays
Visible light waves
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3. Electromagnetic energy invisible
to the human eye is the:
Yellow light
Red light
Blue light
Ultraviolet light
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4. The bending of light rays that
results as light crosses a boundary
from one substance to another.
Reflection
Diffraction
Absorption
Refraction
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5. Wavelength of a wave is defined
as:
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The distance from crest
to crest
One half the distance
from crest to crest
The distance between
the highest and lowest
point.
How often a wave goes
up and down.
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6. If the light from a star is
redshifted the astronomers:
A. The star is moving
away from the
viewer.
B. The star is moving
toward the viewer.
C. The star is not
moving
D. The star is a red
giant.
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Which part of the Electromagnetic
spectrum has a frequency lower
than visible light?
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X-ray
Ultraviolet
Infrared
Gamma
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B.
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More energy
Less energy
Same amount
Gamma is the
speed of light.
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8. How does gamma radiation
compare to the energy of
radiowaves?
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Ultrasound machines are
smaller and use less
energy
The energy in an
ultrasound is directed in
one spot.
X-rays have the same
wavelength as radio waves
X-rays have higher energy
and may damage the fetus.
U
A.
9. Why is it safer for a pregnant
woman to get an ultrasound
instead of an x-ray?
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10. Which type of radiation can be
stopped by a sheet of paper?
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Alpha
Beta
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