Refraction/scattering

Noise Control Sound is a fluctuation of air pressure that can be detected by the human ear. Sound travels through any fluid (e.g., the air) as a compression/expansion wave. This wave travels radially outward in all directions from the sound source. The pressure wave induces an oscillating motion in the transmitting medium that is superimposed on any other net motion it may have. These waves are reflec ted, refracted, scattered, and absorbed as they encounter solid objects. Sound is transmitted through sohds in a complex array of types of elastic waves. Sound is charac terized by its amplitude, frequency, phase, and direction of propagation. 

When a light beam passes a matter the different phenomena are observed, which are schematically illustrated in Figure 2.2. These encompass reflection, diffusion, transmission, refraction, scattering, absorption, and luminescence. 

It is natural at this point to define the faetors limiting the applicability of VM. First, the sample must have certain optical properties, since the technique relies on the reflection, refraction, scattering, and absorption of radiation, for instance, visible light, as is the case for optieal mieroscopy. For emulsions, this means that the sample must be transparent and that the continuous liquid and the droplets must have different refractive indices or different eolors, i.e., properties which make them optically distinguishable. Sec-... 

Three main types of nondestructive spectroscopic techniques are commonly used absorption, emission, and physical techniques based on the modification of rays of electromagnetic energy (refraction, scattering, polarization, and refraction). 

Both effects arise when the PDA system is set up to receive refractively scattered light, as is typical in spray applications, but instead receives reflectively scattered light. These signals are then processed with the phase-diameter relationship based on refraction and thus lead to incorrect size measurements. 

The physics of X-ray refraction are analogous to the well known refraction of light by optical lenses and prisms, governed by Snell s law. The special feature is the deflection at very small angles of few minutes of arc, as the refractive index of X-rays in matter is nearly one. Due to the density differences at inner surfaces most of the incident X-rays are deflected [1]. As the scattered intensity of refraction is proportional to the specific surface of a sample, a reference standard gives a quantitative measure for analytical determinations. 

If the scattering particles are in a dielectric solvent medium with solvent refractive index Uq, we can define the excess... 

In the second broad class of spectroscopy, the electromagnetic radiation undergoes a change in amplitude, phase angle, polarization, or direction of propagation as a result of its refraction, reflection, scattering, diffraction, or dispersion by the sample. Several representative spectroscopic techniques are listed in Table 10.2. 

Equations (10.17) and (10.18) show that both the relative dielectric constant and the refractive index of a substance are measurable properties of matter that quantify the interaction between matter and electric fields of whatever origin. The polarizability is the molecular parameter which is pertinent to this interaction. We shall see in the next section that a also plays an important role in the theory of light scattering. The following example illustrates the use of Eq. (10.17) to evaluate a and considers one aspect of the applicability of this quantity to light scattering. 

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