CHAPTER V. 

 THE SPEED OF A CORPUSCLE AND How IT is ESTIMATED. 



In order to determine how fast corpuscles move, we 

 should consider that during the flight of a corpuscle from 

 the aluminum plate, A, until it passes through the window 

 of the screen, E, energy is being acquired by it from the 

 electric field which exists between the two. plates, A and#, 

 both charged electrodes. This energy may be represented 

 by Ve, where V is the difference in electric potential between 

 the two plates and e the electrical charge on the corpuscle. 

 Now, the kinetic energy of a body may be represented 



also by the familiar formula, ^-. Hence we have, ^~=Ve } 



in which m is the mass of the corpuscle, v its velocity, e its 

 electrical charge, and V the difference of electrical poten- 

 tial between the plate and the screen. Placing V over to 



the other side of the equation, we find that e =^Y- From 

 our equation concerning the magnetic deflection, R=2^, 



G -Li 



it is evident that e must also equal ^. And hence, 

 y^-=^g. Simplify this equation and you will find that 



n TT 



v== Rjj- That is to say: 



Velocity of corpuscle- 06 di f ere ce of P otential 



Radius of circle X magnetic force 



The value of the three terms on the right-hand side of 

 the equation are known; and the problem is solved. 

 So determined, the velocity of the corpuscles is simply 



(59) 



