THE HALL AND CORBINO EFFECTS. 



By E. p. ADAMS. 



{Read April 22, 191 5.) 



About four years ago Professor Corbino^ described some effects 

 which are closely related to the Hall effect. These new effects 

 all have to do with the production of a secondary circular current 

 in a metallic disk when a primary radial current is sent through it, 

 and the disk placed in a magnetic field perpendicular to its plane. 

 The only metal in which Corbino was able to detect any of these 

 effects was bismuth, perhaps owing to lack of sensitiveness in his 

 methods, but more probably because he seems to have neglected to 

 take the precaution of preventing circular currents in a parallel disk 

 used to lead the radial current into the disk under investigation. 

 These circular currents would produce an effect which would largely 

 balance the effect sought. 



Last year Mr. Chapman and P measured this Corbino effect in 

 twelve different metals. In two other metals, tin and zinc, the 

 effect was too small to measure. The method of measurement con- 

 sisted in measuring the current induced in a coil of wire placed 

 parallel to the disk when the radial current was reversed about 

 twenty times a second by a rotating commutator. 



The result of these measurements showed that the circular cur- 

 rent C, produced, was proportional to the magnetic field, H, and to 

 the radial current, /, or 



C = aHI. 



In the magnetic metals and in bismuth a is not constant but it de- 

 pends on the magnetic force. In all the other metals tried a appears 

 to be constant. 



In order to compare this effect with the Hall effect, we may 



^ Physikalische Zeitschrift, XII., pp. 561, 842, 191 1. 

 2 Philosophical Magasine, XXVIII. , p. 692, 1914. 



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