Transcript Slide 1

Pre-lab PowerPoint
Lesson for S.W.A.T. E-lab
It all starts with vibrations!
Vibrations are waves of energy that
move from one place to another.
These vibrations can occur in….
Water – waves on the ocean shore
Electricity – running through a wire
Light – from the Sun or light bulbs
Air – vibrating string in a piano
• Whenever you watch TV, send a text message, or
heat food in a microwave, you are using waves.
Some waves, like sound waves, need molecules to
travel through. This is why you can hear sound in
our atmosphere but not in space.
• Some waves, however, do not need molecules to
travel. These waves are called electromagnetic
waves. These waves can travel through solid
materials - but they can also travel through empty
space.
The word electromagnetic comes from
the two words ‘electricity’ and
‘magnetism’. When an electric field
and magnetic field move together, they
make waves - electromagnetic waves!
Waves go up and down, and they move
forward - like a shaken rope.
(How Long)
(How Tall)
The length of a wave from crest to crest
is called WAVELENGTH. The different
waves of the spectrum can be as small
as the nucleus of an atom, or as big as
a planet!
(How
Long)
(How
Tall)
How many waves move pass a point
in one second is called
FREQUENCY. The more wiggles
the higher the energy.
Different colors
of light are due
to waves of
different length
and frequency
The height of a wave is referred to
as AMPLITUDE.
With sound
waves, the
higher the
amplitude, the
louder the
noise.
(How
Long)
(How Tall)
• There are many types of waves along
the electromagnetic spectrum, from
very long radio waves to very short
gamma rays. We are only able to see a
small portion of this spectrum called
visible light. However, scientific
instruments use the full range of the
electromagnetic spectrum to study and
learn about both Earth and space.
• Radio waves have the longest wavelengths in the
electromagnetic spectrum. They can be as large as a
football field to larger than our planet! They have the
lowest frequency of all the electromagnetic waves. Since
radio waves can carry energy, we use them to transmit
information by changing either the frequency or the
amplitude of the radio wave to encode a message.
• Radio waves are useful because they can travel through
many different materials, like clouds, without being
absorbed.
• Radio telescopes are used to view planets, comets, giant
clouds of gas and dust, stars, and galaxies.
• Microwaves are higher frequency than radio waves. They
range in size from about 1 millimeter to 1 foot long. You
are probably most familiar with them when you heat your
food up in a microwave, but they have a lot more uses
including weather forecasting and cell phones!
Microwaves can even pass through clouds, which make
them an excellent wavelength for transmitting satellite
communications.
• In 1965, two scientists at Bell Labs, Arno Penzias and
Robert Wilson, detected a strange background noise. The
scientists soon realized that they had discovered noise
left over from the Big Bang that began the universe
billions of years ago!
• Infrared waves are about the length of a grain of sand.
While we cannot see infrared, we can sense some of the
energy as heat.
• Infrared light is used in television remote controls and
even in video games. We can use infrared cameras to
study heat loss patterns, such as from a house. This can
help us to better insulate openings such as doors and
windows to keep thermal energy in and reduce the cost
to heat the house.
• Infrared energy can reveal objects in the universe that
cannot be seen in visible light using optical telescopes.
Infrared light is helpful in studying new stars because
often dense gas clouds block their visible light.
• All electromagnetic radiation is light, but we can only see
a small portion of this radiation. This is the part of the
spectrum we call visible light.
• Each color of the visible light spectrum has a different
wavelength. This is why when white light travels through
a prism, the wavelengths separate into the colors of the
rainbow.
• Your color TV has only red, green and blue dots but these
make all the other colors on your screen. Objects appear
to be different colors because they absorb different
amounts of the red, green and blue light. They reflect the
rest of the wavelengths in visible light and this is the
color we see.
• About 43% of the total
radiant energy from
the sun is in the visible
parts of the spectrum.
• Most of the remainder
is in the near-infrared
(49%) and ultraviolet
section (7%).
• Less than 1% of solar
radiation is emitted as
x-rays, gamma waves,
and radio waves.
• Ultraviolet (UV) light has shorter wavelengths than visible
light. Although UV waves are invisible to the human eye,
some animals can see them.
• The Sun is a source of the full spectrum of ultraviolet
radiation, UV-A, UV-B, and UV-C waves. UV-C rays are the
most harmful but are almost completely absorbed by our
atmosphere. UV-B rays are the harmful rays that can
cause our skin to burn. About 95 percent of UV-B rays are
absorbed by ozone in the Earth's atmosphere.
• Young stars shine most of their light in the ultraviolet
wavelength, so scientists are able to study the formation
of new stars using ultraviolet telescopes.
• X-rays have much higher energy and much shorter
wavelengths than ultraviolet light.
• X-rays were first studied in 1895 by a German scientist
named Wilhelm Conrad Roentgen. He discovered that
aiming x-rays through the human body created detailed
images of the bones inside. Because bones are so dense,
they absorb more x-rays than skin does creating shadows
on the x-ray film.
• Some things in space naturally emit x-rays. The hotter the
object is, the shorter the wavelengths that are emitted.
• Earth's atmosphere blocks x-ray radiation. This is beneficial
for us here on Earth, because x-rays are so energetic that
they would harm almost every living thing on earth!
• Gamma rays have the smallest wavelengths and the most
energy of all the waves. They are produced by the hottest
and most energetic objects in the universe.
• On Earth, gamma waves are created by nuclear
explosions, lightning, and radioactive decay.
• Exposure to these high-energy waves can cause damage
to cells in living things. Sometimes, though, these
changes to cells can be helpful. Gamma radiation is used
to kill cancer cells.
• Gamma-ray bursts are the most energetic and luminous
electromagnetic events and can release more energy in
10 seconds than our Sun will emit in its entire 10-billionyear expected lifetime! Scientists can also use gamma
rays to determine the elements on other planets.
• Some waves can be harmful if you are exposed to them for too
long. The side of the spectrum with wavelengths shorter than
visible light tend to be more dangerous to humans because
they can have effects on the cellular level.
• The Sun bombards our Earth constantly with electromagnetic
energy. However, the Earth's atmosphere protects us from
higher energy waves that can be harmful to life.
• Some waves, such as visible light and microwaves, pass
through the atmosphere. While the atmosphere is essential to
protecting life on Earth, it is not helpful when it comes to
studying waves in space. Because it blocks much of the
radiation, instruments have to be positioned above the
atmosphere in order to study higher energy and even some
lower energy sources.
Now let’s see you create your
own electromagnetic
spectrum in the Spectrum
Scramble Activity!