Part 1: Exploring the Spectrum p. 45 Planning Note: Using diffraction gratings to draw the continuous spectra of incandescent- and fluorescent light requires students make qualitative observations only and duplicates activity using spectroscopes in Part 2: Spread the Light, PSLG p. 52. Skip this part of the activity; answer questions re: the EM spectrum only (see section entitled, "Visible Light: Part of the Electromagnetic Spectrum"). Be sure to include challenge problems (use graphics from Colorado website, below): * I.D. gasses in fluorescent lights: argon & mercury Note: Fluorescent lights (classroom ceiling) = 277 volts!!! * I.D. elements in a compound (or in a star) by looking at several spectral signatures superimposed on each other ***See TRG, pp. 111-112, 113-116. Photocopy Assessment_Spectacular-Spectrum_TRGpp111-116_TAK pp. 3-4; TAK = pp. 5-6.*** "For Part 3, select three compounds with different metals (e.g., cupric nitrate, strontium chloride, and sodium chloride) to use as compounds A, B, and C. Identify these compounds for students. Select a fourth compound that contains one of the same metals (Cu, Sr, or Na) to use as an unknown for the students to identify." Compound A. Lithium Chloride (LiCl) <-- reddish flame Compound B. Copper Chloride (CuCl2) <-- green Compound C. Potassium Chloride (KCl) <-- peach/tangerine "Bonus" Compounds: Barium Chloride (BaCl2) <-- light green (like a grannysmith apple) Calcium Chloride (CaCl2) <-- bright orange Compound D. Copper Sulfate (CuSO4) <-- "dealer's choice" When substances are heated, electrons go to higher energy level. As the substance cools, the electrons return to lower energy level, emitting light. The major [spectral bright] lines are as follows: All of the values are in Angstroms. Lithium (Li): 6708 (minor: 6103); Barium (Ba): 4934 (Minor 6141 & 6196); Copper (Cu): 5105-->5218; Potassium (K): 4047 & 4044 (Weak lines); Strontium (Sr): 4078, 4215, 4607 (strong) and lots of moderate intensity bands from 5560-->4700; Calcium (Ca): nothing but weak lines around 4227 and 4455. Reference: the Handbook of Chemistry and Physics. > Optical Spectrum http://en.wikipedia.org/wiki/Optical_spectrum (incl. section entitled, "Spectroscopy") > Emission spectrum http://en.wikipedia.org/wiki/Emission_spectrum Google Search: "bright line spectra" > Spectral Lines Pick an element from the menu to see its spectral signature: http://www.colorado.edu/physics/2000/quantumzone/index.html > Flame test http://en.wikipedia.org/wiki/Flame_test > Absorption Spectra http://www.colorado.edu/physics/2000/quantumzone/fraunhofer.html > Atomic Absorption and Emission Spectra http://csep10.phys.utk.edu/astr162/lect/light/absorption.html > Absorption spectrum http://en.wikipedia.org/wiki/Absorption_spectrum Image: Cumulative-absorption-spectrum-hubble-telescope.jpg http://en.wikipedia.org/wiki/Image:Cumulative-absorption-spectrum- hubble-telescope.jpg Related Articles: http://en.wikipedia.org/wiki/Fluorescent http://en.wikipedia.org/wiki/Fluorescent_lamp http://en.wikipedia.org/wiki/Image:Fluorescent_lighting_spectrum_peaks_ labelled.gif How Stuff Works: How Fluorescent Lamps Work http://www.howstuffworks.com/fluorescent-lamp.htm 2007 http://en.wikipedia.org/wiki/Incandescent_lamp http://en.wikipedia.org/wiki/Fluorescent_lamp <-- see "External links" http://www-istp.gsfc.nasa.gov/Education/wfluor.html http://en.wikipedia.org/wiki/LED http://www.ccrane.com/lights/led-light-bulbs/index.aspx <-- featuring good comparison of efficiency http://en.wikipedia.org/wiki/Meter nanometer: http://en.wikipedia.org/wiki/Meter#SI_prefixes Angstrom: http://en.wikipedia.org/wiki/Meter#Equivalents_in_other_units (1 nanometre = 10 Ångströms) Scale on diffraction gratings is in nanometers; scale on spectroscopes is in abbreviated Angstroms. Google Calculator: 300 nm = ? angstroms 300 nanometers = 3,000 angstroms 700 nanometers = 7,000 angstroms "The numbers 4-7 seen in the spectroscope are shortened versions of the wavelength measurements. The wavelengths for the [spectrum of visible light range] from about 4,000 to 7,500 Angstroms (violet to red). 3000 angstroms = ? cm 3 000 angstroms = 3.0 × 10(-5) centimeters [0.00003 cm or 0.0003 mm] 7000 angstroms = ? cm 7 000 angstroms = 7.0 × 10(-5) centimeters -- PRACTICAL APPLICATIONS: http://www.madsci.org/posts/archives/apr2001/986273704.Ph.r.html Re: Are there any practical uses for gamma rays? "Yes. Many uses. Radiographing is the same as X-raying, but it doesn't require a source of electricity." Remote controls (e.g., for TVs, VCRs, etc.) use infrared light. How Remote Controls Work http://electronics.howstuffworks.com/remote-control2.htm "... usually 980 nanometers." "While infrared remotes are the dominant technology in home-theater applications, there are other niche-specific remotes that work on radio waves instead of light waves. If you have a garage-door opener, for instance, you have an RF remote." Microwave oven http://en.wikipedia.org/wiki/Microwave_oven A microwave oven works by passing microwave radiation, usually at a frequency of 2.45 GHz (a wavelength of 12.24 cm), through the food. Bluetooth runs from 2400-2483.5 MHz. XM uses spectrum from 2332 to 2345 MHz. Wavelength in meters is (approximately) 300 divided by the frequency in megahertz. So these are going to have wavelengths just a little longer than 12.5 cm. 12.5 cm = ? m 12.5 centimeters = 0.125 meters or 1.25 x 10(-1) m <-- on the boundary between microwave & radio wave 12.5 cm = ? nm 12.5 centimeters = 125 000 000 nanometers http://www.wsanford.com/~wsanford/gr8ps/02_yellow/03_heat_on_the_move/ radiation_station/EMSpec.gif -- > BSLG: The Spectacular Spectrum - Part 1: Spread the Light [old BSLG] ("bug zapper"/gas discharge tubes + spectroscopes) 1. incandescent light 2. fluorescent light 3. hydrogen 4. helium 5. nitrogen [or neon] 6. neon (gas tube broken) <-- replaced, 2005-2006) [or mercury] Optional: Sodium (sodium vapor lamps) line of sight | | |-\ | | \ <--- spectroscope | | \ | |____\ v ^ | (small vertical slit) X = light source Related demo ... - Color wheel/fan/white light Demo: "Magic Wheel" - use fan to spin color wheel; colors of the rainbow merge to produce the color white.