Particle model of light

You will compare the wave and particle models of light. 

Compare the wave and particle models of light. What phenomena can only be explained by the particle model ... 

Describe the phenomena that can be explained only by the particle model of light. 

The dual wave-particle model of light accounted for several previously unexplainable phenomena, but scientists still did not understand the relationships among atomic structure, electrons, and atomic emission spectra. Recall that hydrogens atomic emission spectrum is discontinuous that is, it is made up of only certain frequencies of light. Why are the atomic emission spectra of elements discontinuous rather than continuous Niels Bohr, a Danish physicist working in Rutherford s laboratory in 1913, proposed a quantum model for the hydrogen atom that seemed to answer this question. Bohr s model also correctly predicted the frequencies of the lines in hydrogens atomic emission spectrum. 

From this expression for p, we see that the wave and particle models of light are intimately connected. We will see in Section 8-4 that the expression p = hjX applies to all particles, not just photons. 

The dual wave/particle description of light and matter is really just a mathematical model. Since we can t see atoms and observe their behavior directly, the best we can do is to construct a set of mathematical equations that correctly account for atomic properties and behavior. The wave/particle description does this extremely well, even though it is not easily understood using day-to-day experience. 

Line spectra for multi-electron atoms are more complex than the hydrogen line spectrum, and thus are less easily explained in an explicit fashion at a middle school, high school, or even first year undergraduate level. However, discussions of this topic with respect to the hydrogen atom allow for the instructor to point out many important features of rudimentary quantum mechanics. Among these are the quantized nature of the electrons in atoms, the Bohr model of one-electron atoms, the dual wave-particle nature of light, the... 

The solution, proposed by Einstein, was that the discrete energy units, identified by Planck, correspond to quanta of light, called photons, which interact with electrons in the metal surface during direct collision. This dual wave/particle nature of light inspired de Broglie to postulate a similar behaviour for electrons. Experimental observation of electron diffraction confirmed the wave nature of electrons and firmly estabUshed the dual character of all quantum objects as mysterious reality. As the logical pictme of an entity, which is wave as well as particle, is hard to swallow, it has become fashionable to avoid all physical models of quantum events it is considered poor taste to contaminate the quantmn world with classical concepts. This noble idea of the so-called Copenhagen interpretation of quantmn theory has resulted in a probabilistic computational model that, not only defies, but denies comprehension. 

Light behaves as both a wave and a particle. This duality has resulted in the division of optics into physical optics, which describes the wave properties of light geometric optics, which uses rays to model light behavior and quantum optics, which deals with the particle properties of light. Optics uses these theories to describe the behavior of light in the form of refraction, reflection, interference, polarization, and diffraction. 

Quantum Optics. Quantum optics is a division of physics that comes from the application of mathematical models of quantum mechanics to the dual wave and particle nature of light. This area of optics has applications in meteorology, telecommunications, and other industries. 

The Wave Nature of Light 217 The Particle Nature of Light 220 Atomic Spectra 223 Line Spectra and the Rydberg Equation 223 The Bohr Model of the Hydrogen Atom 224 7.4... 

Light can also be described by a particle model (Figure 2.30) that treats light as a stream of photons or tiny packets of light energy. The two models of light are linked by Planck s equation ... 

Modeling of Light Scattering by Irregularly Shaped Particles Using a Ray-Ttadng Method forthcoming publication in Applied Optics , 1991... 

Y.A. Eremin, N.V. Orlov, Modeling of light scattering by nonspherical particles based on discrete sources method, J. Quant. Spectrosc. Radiat. Transfer 60, 451 (1998)... 

At the time that J. J. Thomson conducted his experiments on cathode rays, the nature of the electron was in doubt. Some considered it to be a form of radiation, like light others believed the electron to be a particle. Some of the observations made on cathode rays were used to advance one view or the other. Explain how each of the following properties of cathode rays supports either the wave or the particle model... 

Heller and Tabibian (13) noted that errors, due to laterally scattered light and the corona effect, as large as to cause a 30 reduction in measured turbidity, may result if instruments which are perfectly suitable for ordinary absorption measurements are used for turbidity measurements without proper modifications. To evaluate the performance of our turbidity detector, particle suspensions of various concentrations of several polystyrene latex standards were prepared. Their extinction coefficients were measured using both a bench-top UV spectrophotometer (Beckman, Model 25) and the online detector (Pharmacia). 

That light has a dual nature and behaves either like a wave or like a stream of particle-like photons is a fact we must accept, although it is nonintuitive. But remember, we have no direct experience of the behavior of very small particles such as electrons. Which model we use depends on the observations we are making. The wave model is appropriate when we are considering diffraction and interference experiments, but the particle (photon) model is essential when we are considering the interaction of light with individual atoms or molecules. 

Ackeskog et al. (1993) made the first heat transfer measurements in a scale model of a pressurized bubbling bed combustor. These results shed light on the influence of particle size, density and pressure levels on the fundamental mechanism of heat transfer, e.g., the increased importance of the gas convective component with increased pressure. 

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