Download ELECTROMAGNETIC SPECTRUM

NAME _______________________
PER____
Due Date___________
MAIL BOX ________
Electromagnetic Spectrum
Investigation of Spectrum Gas Tubes with Spectroscopes
BACK GROUND: Every gas gives off a characteristic light when placed across a high electrical field. Spectrum tubes are
built to contain different gaseous atoms or molecules. When a tube is placed into the Spectrum tube Power Supply, the
5,000V field will cause the gases to emit energy in the form of a well-defined light spectrum.
When a gas is excited by the high voltage, an electron will be excited to a higher energy level. When the electron
returns to a lower energy, it simultaneously emits a photon of light. This photon of light is always the same energy since
the energy change is always the same. Therefore, each excited element emits its very own characteristic wavelengths,
determined by energy level differences between electron shells within the electron cloud.
When the spectrum tube is tuned on, it may appear to be a particular color with the unaided eye. However, analysis of
the spectrum with a spectrometer will reveal a series of sharp (monochromatic) emission lines. Spectrum tubes use
research- graded gases and vapors to provide bright-line spectral lines of high clarity. They are designed for optimum
intensity and line resolution when examined in a student grade spectrometer 200line/mm diffraction gradient.
The pressure of the various gases in spectrum tubes is a carefully controlled value that will produce the maximum
quality of brightness and clarity of the spectral lines. The tube life is extended if operation is cyclic and the tubes are
never on for more than 30 seconds.
Flinn Scientific, 2016
[email protected]
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Label :
INTRO: Energy in the form of light waves, comes to us from the sun through the vacuum of space. All matter can radiate
electromagnetic energy under certain circumstances unless it has been cooled to absolute zero.
OBJECTIVE: You will be observing the spectrograms of several light sources. Constructing trigonometric graphs of various
light wavelengths and interpreting that data.
PROCEDURE:
1. Using a spectroscope, observe the bright sky. Never look directly at the sun. In the Box #1 on your data collection
sheet, using colored pencils, draw a spectrogram of what you see.
2. Using a spectroscope, observe the spectrum of a light bulb. Draw this spectrum in Box#2 on the data collection
sheet.
3. Observe the spectra from the gas tube sources supplied by your instructor. Draw and label the spectrograms in the
appropriate boxes on your data collection pages
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Data observation collection sheet
1. _________________________________
2. _________________________________
3. _________________________________
4. _________________________________
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ultraviolet  violet purple
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blue
teal
green
yellow
orange
red
 infrared
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Comparative Anatomy of an Electromagnetic Wave DATA
# of crests ______
# of troughs ______
# of crests ______
# of troughs ______
# of crests ______
# of troughs ______
# of crests ______
# of troughs ______
# of crests ______
# of troughs ______
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Discussion questions: (Answer in complete sentences)
1 - List the colors of the visible portion of the electromagnetic spectrum in order (longest wave length to shortest wave
length.)
2. What is the difference between the spectrum of the sun and that of the light bulb? Elaborate
4. Referring to the spectra of the gas tubes. How is it possible to identify an element by looking at its spectrum?
5. As the frequency of an electromagnetic wave increases, what happens to the wavelength? Hint, refer to page 3.
6a. How does the width of the visible electromagnetic spectrum compare to that of the entire electromagnetic
spectrum?
6b. How many nanometers of difference is there between violet and red? Comment on the significance of wavelength
and provide a numerical answer.
7. How does the wavelength of the infrared portion of the electromagnetic spectrum differ from that of the visible
portion of the spectrum?
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