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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] _________________________________________________________________________________________________ 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 __________________________________________________________________________________________________ Burns 2016 1 Data observation collection sheet 1. _________________________________ 2. _________________________________ 3. _________________________________ 4. _________________________________ 5. _________________________________ 6. _________________________________ ultraviolet violet purple Burns 2016 blue teal green yellow orange red infrared 2 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 ______ Burns 2016 3 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? Burns 2016 4