...Blackbody Radiation At issue here is how radiation interacts with matter. When heated, a solid object glows and emits thermal radiation. As the temperature increases, the object becomes red, then yellow, then white. The thermal radiation emitted by glowing solid objects consists of a continuous distribution of frequencies ranging from infrared to ultraviolet. The continuous pattern of the distribution spectrum is in sharp contrast to the radiation emitted by heated gases; the radiation emitted by gases has a discrete distribution spectrum: a few sharp (narrow), colored lines with no light (i.e., darkness) in between. Understanding the continuous character of the radiation emitted by a glowing solid object constituted one of themajor unsolved problems during the second half of the nineteenth century. All attempts to explain this phenomenon by means of the available theories of classical physics (statistical thermodynamics and classical electromagnetic theory) ended up in miserable failure. This problem consisted in essence of specifying the proper theory of thermodynamics that describes how energy gets exchanged between radiation and matter. When radiation falls on an object, some of it might be absorbed and some reflected. An idealized “blackbody” is a material object that absorbs all of the radiation falling on it, and hence appears as black under reflection when illuminated from outside. When an object is heated, it radiates electromagnetic energy as a result...
Words: 317 - Pages: 2
...lower surfaces were well insulated. For comparison, one plate was considered to be ideal blackbody, which is a perfect absorber and emits; the other one was polished, yielding different radiant properties. According to the procedure, both plates were heated under the lamp from room temperature; plates' temperature was measured with a thermocouple and recorded with LabView Program. To analyze the results, appropriate assumptions were made and correct conservations of energy were chosen. Results and Discussion Based on the data collected in the experiment, Temperature vs Time were plotted for both plates, as shown in figure 1 and figure 3. Our plates were exposed under the lamp for a longer time than claimed in the procedure to reach a relatively steady state, because the lamp we were using was weaker than normal ones. Figure 1, Temperature vs Time for Blackbody Plate Energy terms in the energy balance equation were also calculated and plotted as shown in figure 3 and figure 4. Equations that used to do all the calculations can be found in Appendix A and Appendix B. All the calculations were done using Microsoft Excel. Figure 2, Energy terms vs Time for Blackbody Plate Irradiation, Gtot was calculated to be 1456.95 W/m2. Since the initial temperature of plate surface was measured to be 23.5C, and we assumed G stay constant, so G for Polished plate is the same as G for Blackbody plate. With the Gtot being 1456, α was calculated to be 0.22. All the calculations can...
Words: 402 - Pages: 2
...Blackbody Lab Website for virtual lab http://phet.colorado.edu/sims/blackbody-spectrum/blackbody-spectrum_en.html t? How can you tell? 2. Does the light bulb produce X-rays? How can you tell? 3. In the spectrum made by the light bulb, which wavelength is most intense and what part of the electromagnetic spectrum is this? Wavelength _______________________ Type:_____________________ 4. Given your answer to #3 is an incandescent light bulb very good for its intended use? Explain. Click Save. (The curve will turn yellow) Part II Comparing spectra of different objects. Set the temperature to 615 K, this is comparable to the temperature in a very hot oven. Notice that the RED line is the radiation emitted by the oven. The line should appear flat, but it isn’t. Zoom the y axis in to read .001 and zoom the x-axis out to 12. 1. How is the curve produced by the oven similar to the line produced by the light bulb? 2. How is the curve produced by the oven different from the curve produced by the light bulb? 3. If the power goes out in your kitchen, could you see in the dark using light from the hot oven? Explain. Click Clear to clear the graphs. Set the temperature to 5800K. This is approximately the surface temperature of the sun. You’ll need to zoom in on the horizontal axis and zoom out on the vertical axis. 4. What is the most...
Words: 380 - Pages: 2
...theoretical physicist he started a quest for absolute laws. His favorite absolute law was the law of the conservation of energy which was the first law of thermodynamics that stated that you could take any equal amount of energy and transform it into the same equal amount of energy ideally, meaning no energy was lost. The second law of thermodynamics led him to discover the quantum of action or Planck's constant h. How he came upon his formula for quantum mechanics well be explained as follows. Planck saw that blackbody radiation acted in an absolute sense because it was defined by Kirchhoff as a substance that could absorb almost all radiating energy and emit all that it had absorbed perfectly which is associated with the first law of thermodynamics. By using various experiments and theoretical failures many scientists tried to find the spectral energy distribution to try and draw a diagram of a curve that showed the amount of radiation given off at different frequencies for a blackbody with a given temperature. Then using Wien's law which worked out for high frequencies but didn't work for low, he saw a relationship with the mathematics of the entropy of the radiation in the high- frequency waves in correlation to the low frequency waves and he guessed if he combined the two in the simplest way that he would get a formula that related to the amount of...
Words: 718 - Pages: 3
...More than seven thousand square miles of agriculture were burned. 3,017 homes were lost.7.62 billion dollars were documented in agricultural losses and 117 drought related deaths were noted (Amico). The greenhouse effect is a process by which certain gases in a planet's atmosphere give it a higher temperature than the planet would have otherwise. Light is one form of electromagnetic radiation. From lower energy to higher energy, categories of EM radiation includes radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays. Blackbody radiation is EM radiation given off by all matter, as a function of the matter's temperature. Hotter objects give off more total EM radiation, and also give off a greater fraction of that radiation as higher energy radiation.Since the Sun has a surface temperature of 5,700° C, about 42% of the blackbody radiation it radiates is visible light The Earth also radiates blackbody radiation but almost entirely as infrared light Certain gases in the Earth's atmosphere are transparent to the Sun's visible light but tend to absorb the outgoing infrared light emitted by the Earth. These are called greenhouse gases and include primarily water vapor and carbon dioxide. The atmosphere and the Earth itself become warmer than it would be without the greenhouse gases. Global warming is happening faster than expected and the warming of the planet has a ripple effect on...
Words: 1142 - Pages: 5
...Spacing and relationship between incoming and outgoing rays produces a virtual image which is identical to the real object. Refraction - light rays moving from one transparent medium to another may be bent, or refracted. The amount of refraction of light rays depends upon their angle of incidence in the same way reflection does, and also on specific properties of the different media and how fast light travels in each. 3) Know the evidence for the wave nature of light. Pages 166-170 The wave theory explains how light travels through space, and how it interacts with matter to be reflected, absorbed, or refracted 4) Know the evidence for the particle nature of light. Page 170-171 The particle theory can explain the photoelectric effect and blackbody radiation. 5) No the 5 basic ideas of classic atomic theory Bottom page 180-top of page 181 1. All elements consist of particles called atoms. 2. All atoms of an element are identical and have the same mass. 3. Atoms of each element are different from those of other elements and have different mass. 4. Atoms chemically combine in definite whole-number ratios to form chemical compounds 5. Atoms are...
Words: 545 - Pages: 3
...light largely passes through the atmosphere to warm the planetary surface, which then emits this energy at the lower frequencies of infrared thermal radiation. Infrared radiation is absorbed by greenhouse gases, which in turn re-radiate much of the energy to the surface and lower atmosphere. The mechanism is named after the effect of solar radiation passing through glass and warming a greenhouse, but the way it retains heat is fundamentally different as a greenhouse works by reducing airflow, isolating the warm air inside the structure so that heat is not lost by convection.[2][3][4] If an ideal thermally conductive blackbody was the same distance from the Sun as the Earth is, it would have a temperature of about 5.3 °C. However, since the Earth reflects about 30%[5][6] of the incoming sunlight, this idealized planet's effective temperature (the temperature of a blackbody that would emit the same amount of radiation) would be about −18 °C.[7][8] The surface temperature of this hypothetical planet is 33 °C below Earth's...
Words: 1921 - Pages: 8
...their orbits, therefore, we have to wait for their appropriate alignments to start making our way back to Earth. To date, 90 % of the mass of a spacecraft is fuel. [9] Would have to pass through asteroid belt between Mars and Jupiter But maybe they encounter a piece of debri not that small to shi and they deld against and they try to avoid collision and turn away from the predetermined path, use up too much fuel and realize they won’t quite make it to Titan unless they make a stop to excavate some fuel from an asteroid. After they arrive to Titan. The lander is supposed to poke ice and anchor to the surface or the alternatively float on the lakes because we do not have a justified plan for where it would land… or we do… By studying its blackbody spectra, we anticipate water on titan --- life? Ice blocks/shields the radiation - planetary characteristics Work Cited: [1-9] ESS lecture material ...
Words: 1064 - Pages: 5
...HEAT TRANSFER Modes of Transferring Heat Heat is always transferred when a temperature difference exists between two bodies. There are three basic modes of heat transfer: Conduction involves the transfer of heat by the interactions of atoms or molecules of a material through which the heat is being transferred. Convection involves the transfer of heat by the mixing and motion of macroscopic portions of a fluid. Radiation or radiant heat transfer, involves the transfer of heat by electromagnetic radiation that arises due to the temperature of a body. CONDUCTION Conductive Heat transfer takes place as conduction if there is a temperature gradient in a solid or fluid Conduction will take place if there exist a temperature gradient in a solid (or stationary fluid) medium. Energy is transferred from more energetic to less energetic molecules when neighboring molecules collide. Conductive heat flow occurs in direction of the decreasing temperature since higher temperatures are associated with higher molecular energy. Fourier's Law expressed conductive heat transfer as: q = k A dT / s Where q = heat transfer (W, J/s, Btu/s)A = heat transfer area (m2 , ft2)k =thermal conductivity of the material(W/m.K or W/m℃, Btu/(hroF ft2/ft))dT = temperature difference across the material (K oroC,oF)s = materialism thickness (m, ft) Example of Heat Transfer by Conduction is A plane wall constructed of solid iron with thermal conductivity 70 W/m℃, thickness 50 mm...
Words: 1201 - Pages: 5
...ASTR 100 Chapter ReviewQuestions – Fall 2012 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX Section-1 Check the letter that represents the best answer to each of the multiple choice questions. Answer all questions in this section. Each question is worth 1 point. This section is worth 40 points. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 1. In the scientific method, a hypothesis _____. A. is a statement of fact B. makes a prediction that can be tested C. is usually proven to be correct D. can only be tested once E. none of these 2. Which of the following can't be considered an acceptable hypothesis?" A. Dark matter, (invisible matter which still has gravitational attraction), determines the orbits of stars in the the galaxy B. Mass increases with velocity C. Matter came into existence together with time D. The megagalaxies of the universe will become invisible to each other in time. E. all are acceptable hypotheses 3. A theory is an integrated explanation of numerous “proven”_____. A. facts B. laws C. controls D. hypotheses E. guesses 4. What is the correct sequence of steps in the scientific method? I. State a problem II. Analyze and interpret data III. Develop a hypothesis IV. Share the results with other scientists V. Design and perform experiment to test the hypothesis A. I – II - III - IV – V B. III – I - V – II – IV C. V – IV – III – II – I D. I – III – V – II – IV E. V – II – I – III - IV 5. Ptolemy's model sought to explain retrograde motion by...
Words: 3959 - Pages: 16
...Chapter 10 : The Sun THE SUNS ATMOSPHERE * the sun is so hot that it neither has a liquid or solid matter anywhere inside of it * moving down into the sun there is denser and hotter masses Photosphere (“sphere of light”) * The photosphere is the innermost of layer of the three layers that comprise the suns atmosphere * A gas layer of the sun that has the most visible light * It is about 400 km thick * Density of the photosphere is low by the earth standards about 0.01% as the air we breathe * Photosphere has a blackbody spectrum that corresponds to an average temp of 5800K * The photosphere appears darkest toward the edge or limb of the solar disk , a phenomenon called limb darkening, * This occurs b/c we see regions of different temp at different depths of the photosphere Granules * lightly colored convection features about 100 km in diameter seen constantly in the solar photosphere * time lapse photography shows that granules form, disappear then reform in cylces that last several minutes Chromosphere (“sphere of color”) * is a dim layer of less dense stellar gas that is above the photosphere * It is the layer we normally see * Astronomers can also study the chromosphere through filters that pass light with specific wavelengths strongly emitted by it – but not by the photosphere – or through telescope sensitive to nonvisble wavelengths that the chromosphere emits intensely Spicules - Are...
Words: 7381 - Pages: 30
...pg17-21rad-NEW.qxd 4/12/2005 11:00 AM Page 1 Einstein’s Quanta, Entropy, and the Photoelectric Effect E LEGANT C ONNECTIONS IN P HYSICS “On a Heuristic Point of View Concerning the Production and Transformation of Light”[1] was the first of the five papers published by Albert Einstein in his 1905 “miraculous year.”[2] In that paper, Einstein introduced the concept of “light quanta,” or “photons” as we call them today. The quantum of action was introduced into physics by Max Planck in 1900.[3] Planck derived the thermal equilibrium energy distribution for electromagnetic radiation (also called the “blackbody problem” because of the experimental apparatus). The quantity of interest was dr/df where r denotes the energy density and f the frequency (Fig. 1). No one had been able to derive dr/df from the first principles of statistical mechanics. One serious problem was in the high frequencies, which contributed infinite energy when one integrated over all frequencies to obtain the total energy! Planck thought about the charged particles whose simple harmonic motion generated harmonic electromagnetic waves of the same frequency. He discovered that if he assumed a particle oscillating with frequency f could carry only the discrete energies 0, hf, 2hf, 3hf..., where h was a constant, he could derive the distribution function: dr/df = (8ph/c3) f 3 (e hf/kT − 1)−1 , where c denotes the speed of light in vacuum, k Boltzmann’s constant, and T the absolute...
Words: 3838 - Pages: 16
...A Domestic Solar Hot Water System for Southern Ontario Submitted by: Steve C. Wyndham A.Sc.T. OACETT Membership #: 0856807 Submitted to: OACETT 10 Four Seasons Place, Suite 404 Toronto, ON M9B 6H7 Discipline: Environmental Date Submitted: August 15, 2014 Declaration of Sole Authorship I, Steve Wyndham, confirm that this work submitted for assessment is my own and is expressed in my own words. Any uses made within it of the works of any other author, in any form (ideas, equations, figures, texts, tables, programs), are properly acknowledged at the point of use. A list of the references used is included. Signature: Date: August 18, 2014 Acknowledgments The author would like to acknowledge the use of the Queen’s University On-line Library for access to Research Journals. Abstract Global warming is one of the most potentially disastrous issues facing mankind in the early 21st century, considered to be caused by man-made greenhouse gas emissions. Approximately 30% of the man-made carbon dioxide (CO2) emissions causing global warming is created by the burning of fossil fuels to produce electricity or used as a direct energy source. The use of solar energy to pre-heat water for industrial, commercial and institutional and residential purposes can reduce electricity usage by up to 2% to 6% in southern Ontario. Adding the emissions from using natural gas directly to heat water a figure of 5% to 17% reduction in CO2 emissions can be derived by the...
Words: 11958 - Pages: 48
...Dark Matter Matt Cannon (928) Physics 222 2/15/02 Final Draft Dark Matter The ultimate destiny of our expanding universe depends on how much matter it contains and whether or not the amount of matter will be enough to one day stop the expansion. When astronomers add up all the visible matter (matter that emits or reflects light) in the universe, the result is that there is clearly not enough to stop the expansion of the universe. However, they have discovered over the past several decades that there may be additional matter hidden from view.1 This raises some important questions. What is this dark matter made of? How can it be detected? Astronomers first found substantial observational evidence of unseen matter in the early twentieth century when studying the galaxy M31.2 They discovered that the velocity curve for the outer limbs of the galaxy, which should drop off with increasing radius as mandated by Kepler's Laws and the Virial Theorem, leveled off at approximately 200 km/s. This observation was confirmed in the early 1970’s when radio astronomers found that hydrogen gas at the edge of galaxies moved with roughly the same velocity as hydrogen gas at the center of galaxies. If the visible matter seen in galaxies is the only source of mass then the observed uniform velocity of hydrogen gas is a direct violation of Kepler’s Laws and the conservation of angular momentum. Thus, the simplest explanation (which is usually the correct one) is that the visible matter in...
Words: 2578 - Pages: 11
...Chapter 2 ENERGY CONVERSION AND GENERAL ENERGY ANALYSIS W hether we realize it or not, energy is an important part of most aspects of daily life. The quality of life, and even its sustenance, depends on the availability of energy. Therefore, it is important to have a good understanding of the sources of energy, the conversion of energy from one form to another, and the ramifications of these conversions. Energy exists in numerous forms such as thermal, mechanical, electric, chemical, and nuclear. Even mass can be considered a form of energy. Energy can be transferred to or from a closed system (a fixed mass) in two distinct forms: heat and work. For control volumes, energy can also be transferred by mass flow. An energy transfer to or from a closed system is heat if it is caused by a temperature difference. Otherwise it is work, and it is caused by a force acting through a distance. We start this chapter with a discussion of various forms of energy and energy transfer by heat. We then introduce various forms of work and discuss energy transfer by work. We continue with developing a general intuitive expression for the first law of thermodynamics, also known as the conservation of energy principle, which is one of the most fundamental principles in nature, and we then demonstrate its use. Finally, we discuss the efficiencies of some familiar energy conversion processes, and examine the impact on energy conversion on the environment. Detailed treatments...
Words: 35895 - Pages: 144
