674: Prof. F. A. Lindemann on the 



Since it has sometimes been suggested, however, that these 

 high velocities can only be caused by electrostatic forces,, 

 this point is worth considering, for obviously electrostatic- 

 forces could only act on a cloud with a definite charge. 



It is easy to show that appreciable electrostatic forces- 

 cannot exist on the sun. The outer layers of the chromo- 

 sphere must certainly be highly ionized as will be shown 

 below, so that any charges of the sun as a whole would, 

 rapidly be neutralized by the emission of ions. This w r ould 

 continue until the electrostatic force E <?^ balanced the 

 gravitational attraction M. m/\ Ey being the sun's charge, 

 M its mass, e and m the charge and mass of the ion of 

 valency n, and / the universal constant of gravity. Since 

 hydrogen ions must certainly always be present ne/m cannot 



be less than 2 # 9.10 14 and E =— ~ cannot be greater than 



ne/m 



4'6. 10 11 . Since the capacity of the sun is 6*96. 10 10 the- 

 potential therefore cannot exceed 6*6 E.S.U. or 1980 volts. 



It might be imagined that large differences of potential 

 might be caused by a or ft rays coming from deeper layers. 

 It may be shown that they can only produce a vanishingly 

 small field on account of the high conductivity of the hot 

 ionized gases in the chromosphere. If X is the range of an 

 a particle in a substance of density 1, its range at density p Q 

 is \olpo- The fraction escaping from a depth h is therefore 



27rr 2 sin(/)(l-cos<£) . 



47rr 2 =ism<£(l-cos0) 



i a ll 



where cos <p = — . 



A, 



If the radioactive substance is distributed evenly therefore 

 the total radiation per unit surface will be 



J>- ; < /: 



I 



2 



1 \ 



X) Vl-/*7X 2 d/t = \(7r/8 — 1/6) 



times the number emitted per cm. 3 If ^ is the number of 

 particles emitted per gramme per second, the current is 

 therefore 0*0594 n \ . 2e per cm. 2 



The current due to ft particles may be estimated in a 

 similar way. Since ft particles are absorbed exponentially 

 the total fraction to escape is 





e j dx — ^fi. 



Patting p, the absorption coefficient equal to p fA therefore- 



