280 



are integral multiples of sonic fundamental unit of energy. This implied 

 that energy is emitted from a body in some definite, finite unit and is closely 

 related to his idea that the entropy of a body is a function of the probability 



of its present state 



Conceiving the emission of radiant energy as explosive in type and not 

 continuous, Planck concludes that these energy units may not be neces- 

 sarily of the same magnitude. When a system is vibrating with high fre- 

 quency, a large amount or large unit of energy is associated with it. whereas 

 one of low frequency gives out smaller quantities or units of energy, thus 

 giving us an explanation why so little energy is found in one end of the spec- 

 trum. The fact that some bodies have low thermal capacities at low tem- 

 peratures and that these increase with rise in temperature is indicative of 

 the value of this theory. In this connection it is interesting to note that 

 an explanation of the hydrogen lines in the spectrum has been proposed, 

 based on the idea that no radiations take place except when one electron 

 vibrating changes the form of its orbit, at which instant the energy change 

 of the system is the same. Take the case of the line spectra; it has been 

 asserted that the lines in the spectrum of hydrogen are due to various 

 electronic vibration frequencies in the hydrogen atom, when the equilibrium 

 of this atom has been disturbed; but when this electron is -vibrating about 

 the so-called positive core of the atom that we have an entire system in 

 equilibrium. As long as these vibrations are regular no energy can be sent 

 forth, inasmuch as by this, the equilibrium of the system would be disturbed. 

 With this disturbance there would be a change in its vibration frequency 

 and assuming the radiation emission to be continuous it follows that the 

 frequency change Avill likewise be continuous; but this at once results in the 

 destruction of the lines in the spectrum. An ingenious explanation of these 

 hydrogen lines has been proposed based on Planck's Quantum theory. The 

 electron is conceived of as vibrating about the central core in some form of 

 a stable orbit, probably ellipical in shape. At the instant that one of these 

 orbits changes form radiation will take place. At this instant the radiation 

 will be of one frequency and the energy change will be represented by E =hn 

 where n is frequency of vibrations and h is the universal constant of 

 radiation and is termed by Planck the "operating quantity." 



The problem is a very complex one and has been approached from many 

 angles. The Zeeman effect produced when a light and heat center is placed 

 in a magnetic field offers additional evidence relative to the shifting of line 



