Planck’s hypothesis

Planck s hypothesis of finite elements of energy will have to be made. ... 

Studies of black-body radiation led to Planck s hypothesis of the quantization of electromagnetic radiation. The photoelectric effect provides evidence of the particulate nature of electromagnetic radiation. 

The wave aspects of the photon are completely described by charge-frcc Maxwell equations. Therefore, it is natural to try to reconcile Planck s hypothesis with the wave theory of light. 

Planck s hypothesis is based on the statistical thermodynamics in that the entropy is related to the number of possible energy states for a given energy or thermodynamic probability W ... 

In Planck s hypothesis, h was a constant with physical units energy X frequency = energy X time, but the value of which was yet to be determined. 

We ask you to accept that the second fraction on the right-hand side of Equation 4.4 is the probability that an oscillator of frequency v is activated at a given temperature T. Chapter 9 presents the origin of this probability in the famous Maxwell-Boltzmann distribution, but in this chapter we want to use the result to demonstrate some additional consequences of Planck s hypothesis. 

We now return to the law of cavity radiation. We have seen in the preceding section that Planck s hypothesis has been brilliantly successful not only for cavity radiation, but also in the theory of specific heats. The latter success furnishes additional strong support for the quantum theory. 

Planck s hypothesis that only certain quantities of light energy can be emitted... 

To solve the paradox of blackbody was Planck s hypothesis (inspired) to considered also the radiation s energy as dependent on frequency, with a universal constant of proportionality (h-Planck s constant), as well as the universal Boltzmarm constant appears into the thermal energy. In addition quantified in bimdles of energy, which acknowledge as energy quanta in few words, Planck considered Ihe quantification of electromagnetic radiation as ... 

The spectral profile of this emitted radiation is given by Planck s hypothesis as shown in the following equations ... 

Statistical thermod5rnatnics enables us to express the entropy as a function of the canonical partition function Zc (relation [A2.39], see Appendix 2). This partition function is expressed by relation [A2.36], on the basis of the molecular partition functions. These molecular partition functions are expressed, in relation [A2.21], by the partition functions of translation, vibration and rotation. These are calculated on the basis of the molecule mass and relation [A2.26] for a perfect gas, the vibration frequencies (relation [A2.30]) of its bonds and of its moments of inertia (expression [A2.29]). These data are determined by stud5dng the spectra of the molecules - particularly the absorption spectra in the iirffared. Hence, at least for simple molecules, we are able to calculate an absolute value for the entropy - i.e. with no frame of reference, and in particular without the aid of Planck s hypothesis. 

We have given an initial approximation of the third law on the basis of Planck s hypothesis. We shall come back to this formula after comparing the values of the calorimetric standard entropies (extracted from relation [4.34]) with the absolute entropies measured with spectroscopic data. 

Table 4.5, for a number of substances, gives the values found by calorimetry, calculated using Planck s hypothesis, and the absolute values found by spectroscopic measurements, independent of Planck s hypothesis. We can see two distinct categories of molecules ... 

Evidently, such a result means that we need to review Planck s hypothesis, and therefore the way in which the third law of thermodynamics... 

Planck s hypothesis, 126 pole of a reaction, 69 predominant reactions, 148... 

Planck s hypothesis was confirmed and developed by Einstein s theory of an external photo-effect. 

Albert Einstein was awarded a Nobel Prize in 1921 for his outstanding contribution to physical science in general and especially for the photo-effect theory, which belonged mainly to Einstein and provided convincing confirmation of Planck s hypothesis energy quanta not only in the theory of heat radiation but also in some other physical events. Einstein was also responsible for the concept of a photon which is widely used in modem physics. 

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