Greeks lambda

Electromagnetic radiation has a wave character. The waves move at the speed of light, c, and have characteristics of wavelength X. (Greek lambda ), amplitude, and frequency v (Greek nu ) as illustrated below ... 

In 1923, the Erench physicist Louis de Broglie followed Einstein s lead and advanced the revolutionary idea that if light exhibits properties of particles in motion, then a particle in motion should exhibit the properties of a wave. He proposed that a particle of mass m and speed v has an associated wavelength A (Greek lambda), given by the equation... 

The properties of liquid " He above and below the lambda transition temperature Tx are so completely different that it is almost as though one were dealing with two separate liquids to emphasize the distinction they are referred to as He I and He II respectively. The name of the transition derives from the characteristic shape of the logarithmic singularity that occurs in the specific heat (Fig. 10) at that temperature, which is strongly reminiscent of a Greek lambda. As can be seen from Fig. 9, 7 is weakly pressure dependent, falling towards lower temperatures as the pressure is increased. 

Thermal conductivity, now denoted by the Greek letter lambda (previously known as the fc-value), defines a material s ability to transmit heat, being measured in watts per square meter of surface area for a temperature gradient of one Kelvin per unit thickness of one meter. For convenience in practice, its dimensions Wm/m K be reduced to W/mK, since thickness over area mluF cancels to 1/m. 

All types of waves, whether longitudinal or transverse, can be accurately described by their wavelength and frequency values (see Fig. 6), which are mathematically related to each other by the expression vX = c, where the Greek letter X (lambda) is the wavelength, the Greek letter v (nu) is the frequency of the wave, and c is the velocity of the wave. 

Wavelength is the distance between adjacent crests or high points of a wave. This distance can be measured in metres. However, in chemistry, the unit of wavelength most often used is the nanometre (nm). One nanometre is 10 m. The symbol for wavelength is the Greek letter lambda (X). 

However, the heat capacity near the A-transition has a quite different form (resembling the Greek letter lambda) ... 

A, and vare Greek letters, called phi, lambda, and nu, respectively. 

Very few examples of heat capacity or compressibility behavior of the type shown in the second column have been observed experimentally, however. Instead, these two properties most often are observed to diverge to some very large number at Tt as shown in the third column of Figure 13.1.1 The shapes of these curves bear some resemblance to the Greek letter, A, and transitions that exhibit such behavior have historically been referred to as lambda transitions. 

In figure 11.3. 2, X (the Greek letter lambda) stands for the heat conduction coefficient. This is part of the following formula in which (p (phi) stands for the heat current through the brick. 

Ehrenfest s concept of the discontinuities at the transition point was that the discontinuities were finite, similar to the discontinuities in the entropy and volume for first-order transitions. Only one second-order transition, that of superconductors in zero magnetic field, has been found which is of this type. The others, such as the transition between liquid helium-I and liquid helium-II, the Curie point, the order-disorder transition in some alloys, and transition in certain crystals due to rotational phenomena all have discontinuities that are large and may be infinite. Such discontinuities are particularly evident in the behavior of the heat capacity at constant pressure in the region of the transition temperature. The curve of the heat capacity as a function of the temperature has the general form of the Greek letter lambda and, hence, the points are called lambda points. Except for liquid helium, the effect of pressure on the transition temperature is very small. The behavior of systems at these second-order transitions is not completely known, and further thermodynamic treatment must be based on molecular and statistical concepts. These concepts are beyond the scope of this book, and no further discussion of second-order transitions is given. 

As the name implies, electromagnetic waves exhibit all of the classical properties of waves. Figure 13.2 illustrates the various features of a simple wave. The wavelength, A (lower case Greek letter lambda), is the distance required for a wave to repeat itself. For instance, it is the distance between adjacent peaks (or crests) and also the distance between adjacent troughs. Wavelength is usually measured in meters. The period, T, is the time required for a wave to repeat itself. 

Another type of phase transition is called a lambda transition, because a graph of heat capacity versus temperature for this type of transition resembles the Greek letter X, as shown in Fig. 4. This type of transition is usually associated with a change from an ordered state to a state with some disorder (order-disorder... 

Inspection of Fig. 3.16.5, where we have set w - 2RTA, shows that as the temperature rises there is a marked increase in heat capacity, with a sharp drop off back to zero at T - TA. This figure has approximately the shape of the Greek capital letter A and hence is frequently called a A anomaly TA is known as the lambda point. What Fig. 3.16.5 once more illustrates is... 

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