The Properties of Light

FIGURE 1.1 An example of the electric vector of a light wave. The + and - signs indicate the alternating polarity of the electric vector. The arrows show the wavelength (A.) of the wave. Note where the wave s cycle begins and ends. 

FIGURE 1.2 The infrared spectrum of polystyrene. Note that the x-axis is plotted in wave-number and that the y-axis is in absorbance. 

Since the wavelength has units of distance/cycle and wavenumbers have units of cycles/distance, the two quantities are reciprocals of each other as such  

If X is measured in centimeters, then W is calculated in cm. One of the interesting properties of W is that it is proportional to the energy of a light wave as follows  

E= Light energy in Joules c = The Velocity of light ( 3 x 10 cm/second) h = Planck s constant (6.63 x 10 Joule-second) 

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A hundred years ago it was generally supposed that all the properties of light could be explained in terms of its wave nature. A series of investigations carried out between 1900 and 1910 by Max Planck (1858-1947) (blackbody radiation) and Albert Einstein (1879-1955) (photoelectric effect) discredited that notion. Today we consider light to be generated as a stream of particles called photons, whose energy E is given by the equation... 

The most useful tool for studying the structure of atoms is electromagnetic radiation. What we call light is one form of this radiation. We need to know about the properties of light in order to understand what electromagnetic radiation reveals about atomic stmcture. 

Heinrich Hertz in 1887 who used an oscillating circuit of small dimensions to produce electromagnetic waves which had all of the properties of light waves... 

The International Association for the Properties of Water and Steam (IAPWS) provides internationally accepted values and formulations for the properties of light and heavy steam, water, and selected aqueous solutions for scientific and industrial applications. IAPWS Releases and Guidelines can be obtained online at http //www.iapws.org. 

While discussing the properties of light using a classical description, the formalism is recast as close as possible to the quantum form by introducing the complex analytical signal (r, f), which may be obtained from the real field (r,r) by [18]... 

A full explanation of the properties of light requires both the wave theory of electromagnetic radiation and the quantum theory. Most photochemical processes are best understood in terms of the quantum theory, which says that light is made up of discrete particles called quanta or photons. Each quantum carries an amount of energy, S, determined by the wavelength of the light, A. Equation 13.1, in which h is Planck s constant and c is the speed of light in a vacuum,... 

This resource contains educational activities relating to different forms of energy. Each monster member of the Atom s Family introduces a topic, such as electricity and electrical safety (Frankenstein), the properties of light (Dracula), and fuel conservation and energy transfer (the Wolf Man). 

Coherence Coherence is the property of light emitted from a laser such that it is remarkably uniform in color, polarization, and spatial direction. Spatial coherence allows a laser beam to maintain brightness and narrow width over a great distance. 

Table 3.11 Comparison of the properties of light and heavy water (DIPPR 1997 Marcus 1985)...

The next three chapters deal primarily with the interconversion of various forms of energy. In Chapter 4 we consider the properties of light and... 

Light also has a particle nature—it can best be described as a stream of particles called photons. The properties of light emitted by glowing (red hot) objects and the photoelectric effect can be explained only with Ught as a stream of particles. The energy of the photons ( ) is related to the frequency of the waves (represented by v, Greek nu) ... 

As the first step in our exploration of this revolution in science, we will consider the properties of light, more properly called electromagnetic radiation. 

The properties of light, medium, and heavy oils distilled from pyrolysis oil. are shown in Table 26.7. 

Ellipsometry and reflectometry have in common that information on the adsorbate is extracted from changes induced by this adsorbate in the properties of light after reflection from the surface. At any phase boundary the fractions of light that are reflected and transmitted depend on system properties (such as the refractive Indices of solvent, adsorbate and adsorbent, and the thickness of an adsorbed layer) and conditions that can, within some limits, be chosen (such as the angle of Incidence 8 (counted with respect to the normal to the surface), the wavelength and the polarization). Hence, in principle, adsorbate properties are accessible. 

The properties of light cannot be described completely by analogy with either ordinary waves or ordinary particles. In the discussion of some phenomena the description of light as vave motion is found to be the more useful, and in the discussion of other phenomena the description of light in terms of photons is to be preferred. 

The drawing on the facing page shows a diamond crystal as it might appear to a very small person, with height about equal to the diameter of a carbon atom. (To get this view he would have to change some of the properties of light, as well as those of electrons and atomic nuclei.)... 

We should note that the birth of the quantum theory came about in trying to explain the electronic structure of atoms and the properties of light. It became apparent toward the end of the nineteenth century that the classical laws of physics (classical mechanics as proposed by Isaac Newton in the seventeenth century) could not be used to describe electronic structure. The new theory of quantum mechanics, developed at the beginning of the twentieth century, was a scientific breakthrough that changed the way we view atoms. 

Despite this apparent certainty that hght was a wave. Max Planck and Albert Einstein, at the beginning of the twentieth century, showed that some experiments required the use of a particle model for hght, rather than a wave model. Since both models were necessary for an accurate description of all of the properties of light, scientists today use mathematical equations appropriate to both waves and particles in describing the properties of hght. 

Poly(sulfone) has the characteristic properties such as chemical inertness, excellent strength, stiffness, high resistance to radiations and temperature, dimensional stability, and biocompatibility [2,16,56], These properties resemble the properties of light metals [57], Further, the properties of poly(sulfone) do not change during... 

By and large, gloss is a beneficial property, mainly in household goods, transportation or toys. At present, the property of light reflection is also crucial for the storage of solar energy. 

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