Transcript Electromagnetic Spectrum

Electromagnetic Spectrum
Radio Waves  Gamma Rays
The Parts of the E.M.S.
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Radio Waves
Microwaves
Infrared Waves
Visible Light
UV Light
X Rays
Gamma Rays
Why Are These Waves Alike?
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All these waves travel fast, much faster
than sound
They can travel through a vacuum or
through space (no media is necessary)
They are all transverse waves
They transfer energy by radiation
Lets Sketch the Spectrum
Example
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A deep heat machine like the one used in a
personal trainers office has a common
frequency used of 27.33 MHz. What is the
wavelength of this radiation?
Example 2
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If the north star which is 6.44 x 1018 m
away were to burn out, in what year would
we stop being able to view the star in our
sky?
Example 3
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A wave has a wavelength of 4.0 x 10-7 m
and a speed of 2.5 x 10 8 m/s in a particular
material. A) What is its frequency in this
material? B) The frequency of the wave
does not change as the wave moves from
one material to another. Find the
wavelength of this wave in a vacuum.
Radio Waves
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Long wavelengths
Low frequencies
Used in television and cell phones. Also
FM and AM
Using your voice, computers or other
device, you can change radio wave
frequencies and amplitudes. This is called
Modulation.
Microwaves
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Radio waves with the highest frequency
and energy are microwaves
Used in communication
Also used in cooking. Microwave ovens
transfer energy to the food, causing the
molecules to move around (kinetic energy)
and thus heating the item
Infrared Radiation
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Wavelength is slightly longer than visible
light, so we cannot see them.
The sun emits a large amount of I.R.
radiation.
Warmer objects give off more radiation
than cold objects
Tumors give off more heat than regular
tissue, so infrared cameras are useful.
Visible Radiation
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Also called ____________?
When the sun emits radiation with
frequencies in the range of visible light,
this radiation is viewable by humans
Light can cause chemical reactions like
photosynthesis.
The Colors in the Visible
Spectrum
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Red/ Orange/ Yellow/ Green/ Blue/ Indigo/
Violet
ROYGBIV
UV Radiation
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High energy waves
Greater penetrating power
UV lamps can be used to kill bacteria and
sterilize surgical instruments
Sunscreens are used to help protect us from
sunburns which may lead to skin cancer
What natural filter helps protect us?
X-Rays
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Carry high energy
X-rays can travel through skin and
muscles, but once the waves hit a more
dense area they become absorbed.
The photograph is a negative, and b/c the
bone absorbs the rays, it shines brighter
Gamma Rays
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Highest frequency and smallest wavelength
in the spectrum
They come from the nuclei of radioactive
atoms
In high concentrations, they can destroy
human cells and can be used to kill cancer
cells
In determining the distance to a
cloud, a meteorologist in a TV
station uses radar and notes it
takes 0.24ms between the
sending and return of a radar
pulse. How far away is the
cloud?