DOCSLIB.ORG

ELECTROMAGNETIC SPECTRUM Introduction Contrary to Popular Belief, Outer Space Is Not Empty Space

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
ELECTROMAGNETIC SPECTRUM Introduction Contrary to Popular Belief, Outer Space Is Not Empty Space * Space Based Atronomy.b/w 2/28/01 8:54 AM Page 23 UNIT 2 THE ELECTROMAGNETIC SPECTRUM Introduction Contrary to popular belief, outer space is not empty space. It is filled with electro- magnetic radiation that crisscrosses the universe. This radiation comprises the spectrum of energy ranging from radio waves on one end to gamma rays on the other. It is called the electromagnetic spectrum because this radiation is associat- ed with electric and magnetic fields that transfer energy as they travel through space. Because humans can see it, the most familiar part of the electromagnetic spectrum is visible light—red, orange, yellow, green, blue, and violet. Like expanding ripples in a pond after a pebble Electromagnetic radiation has properties of both has been tossed in, electromagnetic radiation waves and particles. What we detect depends on the travels across space in the form of waves. These method we use to study it. The beautiful colors that waves travel at the speed of light—300,000 kilo- appear in a soap film or in the dispersion of light meters per second. Their wavelengths, the dis- from a diamond are best described as waves. The tance from wave crest to wave crest, vary from light that strikes a solar cell to produce an electric thousands of kilometers across (in the case of current is best described as a particle. When the longest radio waves) to fractions of a described as particles, individual packets of electro- nanometer, in the cases of the smallest x-rays magnetic energy are called photons. The amount of and gamma rays. energy a photon of light contains depends upon its wavelength. Electromagnetic radiation with long Space-Based Astronomy Activity Guide for Science, Mathematics, and Technology Education 23 * Space Based Atronomy.b/w 2/28/01 8:54 AM Page 24 billionth. Thus 700 nanometers is a distance equal to 700 billionths or 7 x 10-7 meter.) Visible light is a very narrow band of radiation ranging from 400 to 700 nanometers. For comparison, it would take 50 visible light waves arranged end to end to span the thickness of a sheet of household plastic wrap. Below visible light is the slightly broader band of ultraviolet light that lies between 10 and 300 nanometers. X-rays follow ultraviolet light and diminish into the hundred-billionth of a meter range. Gamma rays fall in the trillionth of a meter range. The wavelengths of x-rays and gamma rays are so tiny that scientists use another unit, the electron volt, to describe them. This is the energy that an electron gains when it falls through a potential difference, or voltage, of one volt. It works out that one electron volt has a wavelength of about 0.0001 centimeters. X-rays range from 100 elec- tron volts (100 eV) to thousands of electron volts. Gamma rays range from thousands of elec- tron volts to billions of electron volts. Using the Electromagnetic Spectrum All objects in space are very distant and difficult for humans to visit. Only the Moon has been vis- ited so far. Instead of visiting stars and planets, astronomers collect electromagnetic radiation These two views of the constellation Orion dramatically illustrate the differ- from them using a variety of tools. Radio dishes ence between what we are able to detect in visible light from Earth’s surface capture radio signals from space. Big telescopes and what is detectable in infrared light to a spacecraft in Earth orbit. Photo on Earth gather visible and infrared light. Credits: Akira Fujii—visible light image; Infrared Astronomical Satellite— Interplanetary spacecraft have traveled to all the infrared image. planets in our solar system except Pluto and have landed on two. No spacecraft has ever brought wavelengths contains little energy. Electro-magnet- back planetary material for study. They send ic radiation with short wavelengths contains a great back all their information by radio waves. amount of energy. Virtually everything astronomers have learned Scientists name the different regions of the elec- about the universe beyond Earth depends on the tromagnetic spectrum according to their wave- information contained in the electromagnetic lengths. (See figure 1.) Radio waves have the radiation that has traveled to Earth. For example, longest wavelengths, ranging from a few centime- when a star explodes as in a supernova, it emits ters from crest to crest to thousands of kilometers. energy in all wavelengths of the electromagnetic Micro-waves range from a few centimeters to spectrum. The most famous supernova is the about 0.1 cm. Infrared radiation falls between stellar explosion that became visible in 1054 and 700 nanometers and 0.1 cm. (Nano means one produced the Crab Nebula. Electromagnetic National Aeronautics 24 and Space Administration * Space Based Atronomy.b/w 2/28/01 8:54 AM Page 25 Figure 1: Electromagnetic Spectrum radiation from radio to gamma rays has been have yet to understand the highly energetic detected from this object, and each section of the engines in the centers of these strange objects. spectrum tells a different piece of the story. Ultraviolet light studies have mapped the hot gas For most of history, humans used only visible near our Sun (within about 50 light years). The light to explore the skies. With basic tools and high energy end of the spectrum—x-rays and the human eye, we developed sophisticated gamma rays—provide scientists with information methods of time keeping and calendars. about processes they cannot reproduce here on Telescopes were invented in the 17th century. Earth because they lack the required power. Astronomers then mapped the sky in greater Nuclear physicists use strange stars and galaxies as a detail––still with visible light. They learned laboratory. These objects are pulsars, neutron stars, about the temperature, constituents, distribu- black holes, and active galaxies. Their study helps tion, and the motions of stars. scientists better understand the behavior of matter at extremely high densities and temperatures in the In the 20th century, scientists began to explore the presence of intense electric and magnetic fields. other regions of the spectrum. Each region provid- ed new evidence about the universe. Radio waves Each region of the electromagnetic spectrum pro- tell scientists about many things: the distribution of vides a piece of the puzzle. Using more than one gases in our Milky Way Galaxy, the power in the region of the electromagnetic spectrum at a time great jets of material spewing from the centers of gives scientists a more complete picture. For some other galaxies, and details about magnetic example, relatively cool objects, such as star-form- fields in space. The first radio astronomers unex- ing clouds of gas and dust, show up best in the pectedly found cool hydrogen gas distributed radio and infrared spectral region. Hotter objects, throughout the Milky Way. Hydrogen atoms are such as stars, emit most of their energy at visible the building blocks for all matter. The remnant and ultraviolet wavelengths. The most energetic radiation from the Big Bang, the beginning of the objects, such as supernova explosions, radiate universe, shows up in the microwave spectrum. intensely in the x-ray and gamma ray regions. Infrared studies (also radio studies) tell us about There are two main techniques for analyzing molecules in space. For example, an infrared starlight. One is called spectroscopy and the search reveals huge clouds of formaldehyde in other photometry. Spectroscopy spreads out the space, each more than a million times more mas- different wavelengths of light into a spectrum for sive than the Sun. Some ultraviolet light comes study. Photometry measures the quantity of light from powerful galaxies very far away. Astronomers in specific wavelengths or by combining all Space-Based Astronomy Activity Guide for Science, Mathematics, and Technology Education 25 * Space Based Atronomy.b/w 2/28/01 8:54 AM Page 26 Transparency of Earth’s Atmosphere RADIO MICROWAVE INFARED VISIBLE UV X-RAYS GAMMA RAYS 400 200 50 12 6 3 SEA LEVEL 42 -2 -4 -6 -8 -10 -12 10 101101010 10 10 10 Wavelengths (meters) Figure 2: Transparency of Earth’s Atmosphere wavelengths. Astronomers use many filters in Unit Goals their work. Filters help astronomers analyze par- • To investigate the visible light spectrum. ticular components of the spectrum. For exam- • To demonstrate the relationship between energy ple, a red filter blocks out all visible light wave- and wavelength in the electromagnetic spectrum. lengths except those that fall around 600 nanometers (it lets through red light). Teaching Strategy Unfortunately for astronomical research, Earth’s Because of the complex apparatus required to study atmosphere acts as a filter to block most wave- some of the wavelengths of the electromagnetic lengths in the electromagnetic spectrum. (See spectrum and the danger of some of the radiation, Unit 1.) Only small portions of the spectrum only the visible light spectrum will be studied in the actually reach the surface. (See figure 2.) More activities that follow. Several different methods for pieces of the puzzle are gathered by putting displaying the visible spectrum will be presented. observatories at high altitudes (on mountain Some of the demonstrations will involve sunlight, tops) where the air is thin and dry, and by flying but a flood or spotlight may be substituted. For best instruments on planes and balloons. By far the results, these activities should be conducted in a best viewing location is outer space. room where there is good control of light. National Aeronautics 26 and Space Administration * Space Based Atronomy.b/w 2/28/01 8:54 AM Page 27 ACTIVITY: Simple Spectroscope Description: A basic hand-held spectroscope is made from a diffraction grating and a paper tube.
Load more

Recommended publications
  • Absorption of Light Energy Light, Energy, and Electron Structure SCIENTIFIC
    Absorption of Light Energy Light, Energy, and Electron Structure SCIENTIFIC Introduction Why does the color of a copper chloride solution appear blue? As the white light hits the paint, which colors does the solution absorb and which colors does it transmit? In this activity students will observe the basic principles of absorption spectroscopy based on absorbance and transmittance of visible light. Concepts • Spectroscopy • Visible light spectrum • Absorbance and transmittance • Quantized electron energy levels Background The visible light spectrum (380−750 nm) is the light we are able to see. This spectrum is often referred to as “ROY G BIV” as a mnemonic device for the order of colors it produces. Violet has the shortest wavelength (about 400 nm) and red has the longest wavelength (about 650–700 nm). Many common chemical solutions can be used as filters to demonstrate the principles of absorption and transmittance of visible light in the electromagnetic spectrum. For example, copper(II) chloride (blue), ammonium dichromate (orange), iron(III) chloride (yellow), and potassium permanganate (red) are all different colors because they absorb different wave- lengths of visible light. In this demonstration, students will observe the principles of absorption spectroscopy using a variety of different colored solutions. Food coloring will be substituted for the orange and yellow chemical solutions mentioned above. Rare earth metal solutions, erbium and praseodymium chloride, will be used to illustrate line absorption spectra. Materials Copper(II) chloride solution, 1 M, 85 mL Diffraction grating, holographic, 14 cm × 14 cm Erbium chloride solution, 0.1 M, 50 mL Microchemistry solution bottle, 50 mL, 6 Potassium permanganate solution (KMnO4), 0.001 M, 275 mL Overhead projector and screen Praseodymium chloride solution, 0.1 M, 50 mL Red food dye Water, deionized Stir rod, glass Beaker, 250-mL Tape Black construction paper, 12 × 18, 2 sheets Yellow food dye Colored pencils Safety Precautions Copper(II) chloride solution is toxic by ingestion and inhalation.
    [Show full text]
  • The Electromagnetic Spectrum
    The Electromagnetic Spectrum Wavelength/frequency/energy MAP TAP 2003-2004 The Electromagnetic Spectrum 1 Teacher Page • Content: Physical Science—The Electromagnetic Spectrum • Grade Level: High School • Creator: Dorothy Walk • Curriculum Objectives: SC 1; Intro Phys/Chem IV.A (waves) MAP TAP 2003-2004 The Electromagnetic Spectrum 2 MAP TAP 2003-2004 The Electromagnetic Spectrum 3 What is it? • The electromagnetic spectrum is the complete spectrum or continuum of light including radio waves, infrared, visible light, ultraviolet light, X- rays and gamma rays • An electromagnetic wave consists of electric and magnetic fields which vibrates thus making waves. MAP TAP 2003-2004 The Electromagnetic Spectrum 4 Waves • Properties of waves include speed, frequency and wavelength • Speed (s), frequency (f) and wavelength (l) are related in the formula l x f = s • All light travels at a speed of 3 s 108 m/s in a vacuum MAP TAP 2003-2004 The Electromagnetic Spectrum 5 Wavelength, Frequency and Energy • Since all light travels at the same speed, wavelength and frequency have an indirect relationship. • Light with a short wavelength will have a high frequency and light with a long wavelength will have a low frequency. • Light with short wavelengths has high energy and long wavelength has low energy MAP TAP 2003-2004 The Electromagnetic Spectrum 6 MAP TAP 2003-2004 The Electromagnetic Spectrum 7 Radio waves • Low energy waves with long wavelengths • Includes FM, AM, radar and TV waves • Wavelengths of 10-1m and longer • Low frequency • Used in many
    [Show full text]
  • Including Far Red in an LED Lighting Spectrum
    technically speaking BY ERIK RUNKLE Including Far Red in an LED Lighting Spectrum Far red (FR) is a one of the radiation (or light) wavebands larger leaves can be desired for other crops. that regulates plant growth and development. Many people We have learned that blue light (and to a smaller extent, consider FR as radiation with wavelengths between 700 and total light intensity) can influence the effects of FR. When the 800 nm, although 700 to 750 nm is, by far, the most active. intensity of blue light is high, adding FR only slightly increases By definition, FR is just outside the photosynthetically active extension growth. Therefore, the utility of including FR in an radiation (PAR) waveband, but it can directly and indirectly indoor lighting spectrum is greater under lower intensities increase growth. In addition, it can accelerate of blue light. One compelling reason to deliver at least some flowering of some crops, especially long-day plants, FR light indoors is to induce early flowering of young plants, which are those that flower when the nights are short. especially long-day plants. As we learn more about the effects of FR on plants, growers sometimes wonder, is it beneficial to include FR in a light-emitting diode (LED) spectrum? "As the DLI increases, Not surprisingly, the answer is, it depends on the application and crop. In the May 2016 issue of GPN, I wrote about the the utility of FR in effects of FR on plant growth and flowering (https:// bit.ly/2YkxHCO). Briefly, leaf size and stem length photoperiodic lighting increase as the intensity of FR increases, although the magnitude depends on the crop and other characteristics of the light environment.
    [Show full text]
  • Electromagnetic Spectrum
    Electromagnetic Spectrum Why do some things have colors? What makes color? Why do fast food restaurants use red lights to keep food warm? Why don’t they use green or blue light? Why do X-rays pass through the body and let us see through the body? What has the radio to do with radiation? What are the night vision devices that the army uses in night time fighting? To find the answers to these questions we have to examine the electromagnetic spectrum. FASTER THAN A SPEEDING BULLET MORE POWERFUL THAN A LOCOMOTIVE These words were used to introduce a fictional superhero named Superman. These same words can be used to help describe Electromagnetic Radiation. Electromagnetic Radiation is like a two member team racing together at incredible speeds across the vast regions of space or flying from the clutches of a tiny atom. They travel together in packages called photons. Moving along as a wave with frequency and wavelength they travel at the velocity of 186,000 miles per second (300,000,000 meters per second) in a vacuum. The photons are so tiny they cannot be seen even with powerful microscopes. If the photon encounters any charged particles along its journey it pushes and pulls them at the same frequency that the wave had when it started. The waves can circle the earth more than seven times in one second! If the waves are arranged in order of their wavelength and frequency the waves form the Electromagnetic Spectrum. They are described as electromagnetic because they are both electric and magnetic in nature.
    [Show full text]
  • Resonance Enhancement of Raman Spectroscopy: Friend Or Foe?
    www.spectroscopyonline.com ® Electronically reprinted from June 2013 Volume 28 Number 6 Molecular Spectroscopy Workbench Resonance Enhancement of Raman Spectroscopy: Friend or Foe? The presence of electronic transitions in the visible part of the spectrum can provide enor- mous enhancement of the Raman signals, if these electronic states are not luminescent. In some cases, the signals can increase by as much as six orders of magnitude. How much of an enhancement is possible depends on several factors, such as the width of the excited state, the proximity of the laser to that state, and the enhancement mechanism. The good part of this phenomenon is the increased sensitivity, but the downside is the nonlinearity of the signal, making it difficult to exploit for analytical purposes. Several systems exhibiting enhancement, such as carotenoids and hemeproteins, are discussed here. Fran Adar he physical basis for the Raman effect is the vibra- bound will be more easily modulated. So, because tional modulation of the electronic polarizability. electrons are more loosely bound than electrons, the T In a given molecule, the electronic distribution is polarizability of any unsaturated chemical functional determined by the atoms of the molecule and the electrons group will be larger than that of a chemically saturated that bind them together. When the molecule is exposed to group. Figure 1 shows the spectra of stearic acid (18:0) and electromagnetic radiation in the visible part of the spec- oleic acid (18:1). These two free fatty acids are both con- trum (in our case, the laser photons), its electronic dis- structed from a chain of 18 carbon atoms, in one case fully tribution will respond to the electric field of the photons.
    [Show full text]
  • W Aves SCIENCE: Electromagnetic Spectrum
    Keyword Definition Key facts to remember: electromagneti A group of waves that all travel at the same speed in All EM (electromagnetic) waves are transverse waves. c waves a vacuum, and are all transverse. frequency The number of vibrations (or the number of waves) Al l EM waves travel at the same speed (velocity) through a vacuum per second. One hertz (Hz) is one wave per second. (space) at 300 million m/s. infrared (IR) EM radiation that has a longer wavelength than EM waves are grouped based on their wavelengths and frequency. visible. We can feel infrared radiation as warmth. There are 7 basic EM waves. Radio waves, microwaves, infrared, visible light, UV, Xrays , gamma waves. SCIENCE: Waves interface The boundary between two materials. KS4 : AutumnKS4 Term KS4 : AutumnKS4 Term Our eyes can only detect a small part of this spectrum –visible light. refraction The change in direction when a wave goes from one medium to another. Different colours of light have different wavelengths from longest to transverse A wave in which the vibrations are at right angles to shortest: red, orange, yellow, green, blue, indigo, violet. (ROYGBIV) wave the direction the wave is travelling. or pneumonic; Richard Of York Gave Battle In Vain) ultraviolet (UV) EM radiation that has a shorter wavelength than visible light. Used to detect forged bank notes. vacuum A place where there is no matter at all. visible light Electromagnetic waves that can be detected by the human eye. gamma rays Electromagnetic radiation with the shortest SCIENCE: Electromagnetic Spectrum Electromagnetic SCIENCE: wavelengths and highest frequencies.
    [Show full text]
  • UNIT -1 Microwave Spectrum and Bands-Characteristics Of
    UNIT -1 Microwave spectrum and bands-characteristics of microwaves-a typical microwave system. Traditional, industrial and biomedical applications of microwaves. Microwave hazards.S-matrix – significance, formulation and properties.S-matrix representation of a multi port network, S-matrix of a two port network with mismatched load. 1.1 INTRODUCTION Microwaves are electromagnetic waves (EM) with wavelengths ranging from 10cm to 1mm. The corresponding frequency range is 30Ghz (=109 Hz) to 300Ghz (=1011 Hz) . This means microwave frequencies are upto infrared and visible-light regions. The microwaves frequencies span the following three major bands at the highest end of RF spectrum. i) Ultra high frequency (UHF) 0.3 to 3 Ghz ii) Super high frequency (SHF) 3 to 30 Ghz iii) Extra high frequency (EHF) 30 to 300 Ghz Most application of microwave technology make use of frequencies in the 1 to 40 Ghz range. During world war II , microwave engineering became a very essential consideration for the development of high resolution radars capable of detecting and locating enemy planes and ships through a Narrow beam of EM energy. The common characteristics of microwave device are the negative resistance that can be used for microwave oscillation and amplification. Fig 1.1 Electromagnetic spectrum 1.2 MICROWAVE SYSTEM A microwave system normally consists of a transmitter subsystems, including a microwave oscillator, wave guides and a transmitting antenna, and a receiver subsystem that includes a receiving antenna, transmission line or wave guide, a microwave amplifier, and a receiver. Reflex Klystron, gunn diode, Traveling wave tube, and magnetron are used as a microwave sources.
    [Show full text]
  • Light and the Electromagnetic Spectrum
    © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION © JonesLight & Bartlett and Learning, LLCthe © Jones & Bartlett Learning, LLC NOTElectromagnetic FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION4 Spectrum © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALEJ AMESOR DISTRIBUTIONCLERK MAXWELL WAS BORN IN EDINBURGH, SCOTLANDNOT FOR IN 1831. SALE His ORgenius DISTRIBUTION was ap- The Milky Way seen parent early in his life, for at the age of 14 years, he published a paper in the at 10 wavelengths of Proceedings of the Royal Society of Edinburgh. One of his first major achievements the electromagnetic was the explanation for the rings of Saturn, in which he showed that they con- spectrum. Courtesy of Astrophysics Data Facility sist of small particles in orbit around the planet. In the 1860s, Maxwell began at the NASA Goddard a study of electricity© Jones and & magnetismBartlett Learning, and discovered LLC that it should be possible© Jones Space & Bartlett Flight Center. Learning, LLC to produce aNOT wave FORthat combines SALE OR electrical DISTRIBUTION and magnetic effects, a so-calledNOT FOR SALE OR DISTRIBUTION electromagnetic wave.
    [Show full text]
  • Critical Thinking Activity: the Electromagnetic Spectrum
    Student Sheet 1 CRITICAL THINKING ACTIVITY: THE ELECTROMAGNETIC SPECTRUM There are many kinds of energy in the universe. The energy given off from the sun is radiant energy, scientifically called electromagnetic radiation. Produced by nuclear reactions at the core of the sun, this energy streams from the surface of the sun in waves of different lengths. The shortest and longest wavelengths are invisible to our eyes, but the medium wavelengths are the visible radiation we call sunlight. Most of the sun’s energy is released in these visible wavelengths. All substances have kinetic energy that is expressed by vibrations of their atoms or molecules. The vibrations result in radiation. The electromagnetic (EM) spectrum is a name given to all of the different types of radiation. Electromagnetic radiation is energy that spreads out as it travels. Visible light radiation that comes from a lamp in someone’s house or radio wave radiation that comes from a radio station are two types of electromagnetic radiation. Other examples of EM radiation are microwaves, infrared and ultraviolet radiation, X- rays and gamma rays. Hotter, more energetic objects and events create higher energy radiation than cool objects. Only extremely hot objects or particles moving at very high speeds can create high-energy radiation like X-rays and gamma rays. 1 Student Sheet 2 A common assumption is that radio waves are completely different than X-rays and gamma rays. They are produced in very different ways, and we detect them in different ways. However, radio waves, visible light, X-rays, and all the other parts of the electromagnetic spectrum are fundamentally the same.
    [Show full text]
  • Which Regions of the Electromagnetic Spectrum Do Plants Use to Drive Photosynthesis?
    Which regions of the electromagnetic spectrum do plants use to drive photosynthesis? Green Light: The Forgotten Region of the Spectrum. In the past, plant physiologists used green light as a safe light during experiments that required darkness. It was assumed that plants reflected most of the green light and that it did not induce photosynthesis. Yes, plants do reflect green light but human vision sensitivity peaks in the green region at about 560 nm, which allows us to preferentially see green. Plants do not reflect all of the green light that falls on them but they reflect enough for us to detect it. Read on to find out what the role of green light is in photosynthesis. The electromagnetic spectrum: Light Visible light ranges from low blue to far-red light and is described as the wavelengths between 380 nm and 750 nm, although this varies between individuals. The region between 400 nm and 700 nm is what plants use to drive photosynthesis and is typically referred to as Photosynthetically Active Radiation (PAR). There is an inverse relationship between wavelength and quantum energy, the higher the wavelength the lower quantum energy and vice versa. Plants use wavelengths outside of PAR for the phenomenon known as photomorphogenesis, which is light regulated changes in development, morphology, biochemistry and cell structure and function. The effects of different wavelengths on plant function and form are complex and are proving to be an interesting area of study for many plant scientists. The use of specific and adjustable LEDs allows us to tease apart the roles of specific areas of the spectrum in photosynthesis.
    [Show full text]
  • 10 Comparing Colors LABORATORY 1 C L a S S S E S S I O N
    10 Comparing Colors LABORATORY 1 CLASS SESSION ACTIVITY OVERVIEW NGSS RATIONALE In this activity, students first learn that visible light can be separated into different colors. Students then conduct an investigation to collect evidence that indicates that different colors of light carry different amounts of energy. From the results of their investigation, students conclude that higher frequencies of light carry more energy. In their final analysis, students apply the practice of analyzing and inter- preting data as they examine light transmission graphs for three different sunglass lenses. It is through this analysis that students engage with the crosscutting con- cept of structure and function as they determine which sunglass lens provides the best protection for the eyes. NGSS CORRELATION Disciplinary Core Ideas PS-4.B Wave Properties: When light shines on an object, it is reflected, absorbed, or transmitted through the object, depending on the object’s material and the frequency (color) of the light. PS-4.B Wave Properties: A wave model of light is useful for explaining brightness, color, and the frequency-dependent bending of light at a surface between media. Science and Engineering Practices Planning and Carrying Out Investigations: Conduct an investigation to produce data to serve as the basis for evidence that meets the goals of an investigation. Crosscutting Concepts Structure and Function: Structures can be designed to serve particular functions by taking into account properties of different materials, and how materials can be shaped and used. WAVES 3 ACTIVITY 10 COMPARING COLORS Common Core State Standards—ELA/Literacy RST.6-8.3 Follow precisely a multi-step procedure when carrying out experiments, taking measurements, or performing technical tasks.
    [Show full text]
  • Why Is the Sky Purple?
    A laboratory experiment from the Why is Little Shop of Physics at Colorado State University the sky CMMAP purple? Reach for the sky. Overview Necessary materials: Of course, you expect the question to be “why is the sky blue?” That’s the classic version. • 1 “sunset egg” • A white light flashlight And here’s the classic answer: scattering. We’ll talk about what this word means and how it leads to sky color, but we will also see that the The most crucial piece for this experiment is the light from the sky actually contains a bit more “sunset egg.” The small-scale structure of these violet than it does blue! So why do we see glori- glass “eggs” works well to demonstrate the differ- ous blue skies rather than a purple firmament ential scattering that leads to the color of the sky when we gaze up into Earth’s atmosphere? and the color of the sunset. Theory You can find them at rock and nature shops, or you can purchase them in bulk from Pelham Grayson The first person to correctly work out the de- (www.pelhamgrayson.com) under “Magic Feng tails of the process that gives rise to the color of Shui Eggs”. the sky was the English physicist, Lord John Rayleigh, working in the late 1800’s. Rayleigh correctly surmised that the blue color of the sky was a result of scattering. As light enters our atmosphere on its journey from the sun, it interacts with air molecules and is redirected. This redirection is more pronounced for shorter wavelengths toward the blue, or violet, end of the spectrum.
    [Show full text]